Method for the manufacturing of sintered metal parts having a densified surface

A technology of densification and parts, which is applied in the field of manufacturing sintered metal parts, can solve the problems of reduced tooth surface contact fatigue strength, reduced bending fatigue strength, and large energy consumption, so as to improve mechanical properties, reduce pressing steps, and increase surface densification effect of depth

Inactive Publication Date: 2006-11-01
HOGANAS AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem with gears formed from powder metal processes is that powder metal gears have reduced bending fatigue strength in the tooth root region of the gear and the contact of the tooth flanks compared to gears formed from bar stock by machining or casting Reduced fatigue strength
According to the patent, sintering can be carried out at a temperature of 1120°C, ie at conventional sintering temperatures, but since two sintering steps are proposed, the energy consumption will be considerable

Method used

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  • Method for the manufacturing of sintered metal parts having a densified surface
  • Method for the manufacturing of sintered metal parts having a densified surface
  • Method for the manufacturing of sintered metal parts having a densified surface

Examples

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example 1

[0025] The cylinders were pressed from a powder metallurgical composition comprising pre-alloyed powder Astaloy Mo with 0.3% graphite additive and an amide wax lubricant. In order to obtain a density higher than 7.2g / cm 3 The green body is pressed at high speed; in order to make the density up to 7.2g / cm 3 , using conventional uniaxial pressing. The pillars were sintered at 1120°C for 30 minutes in an atmosphere of 90% nitrogen and 10% hydrogen. Surface densification was performed by radial rolling, during which the diameter was reduced by 0.3 mm. Densification depth was assessed using image analysis and was defined as the shortest distance from the surface to the point at which the density had decreased to 98% of theoretical density.

[0026] available from figure 1 The relationship between the sintered density of the blank and the densification depth obtained for the densified part is seen in .

example 2

[0028] A photomicrograph of the pressed, sintered and surface-densified columns is shown in FIG. 2 . Figure 2a The columnar body in is pressed by conventional means to reach 7.0g / cm 3 and the obtained densification depth is 1 mm, while shown in Figure 2b The columnar body in it reaches 7.5g / cm through high-speed pressing 3 and a densification depth of 2 mm was obtained.

example 3

[0030] Cylindrical bodies pressed at high speed at 90 / 10N 2 / H 2 sintered at 1120°C for 30 minutes in an atmosphere of 1120°C, and then surface densified by rolling in a two-roll calender. The diameter is reduced by 0.3 mm during the rolling process. Polished cross-sections of the rolled cylinders were examined in a lightweight light microscope, and image analysis was used to assess the densification depth. The depth of densification obtained by rolling the cylinders is shown in Table 1 .

[0031] sample

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Abstract

The present invention concerns a method for producing powder metal parts having a densified surface. The method comprises the steps: - compacting an iron-based powder by high velocity compacting technique to a density above 7.2 g / cm<3> - sintering the parts -subjecting the parts to a surface densifying process.

Description

technical field [0001] The invention relates to a method for producing sintered metal parts. More specifically, the invention relates to a method for manufacturing sintered metal parts with densified surfaces. Background technique [0002] One area that will see growth in the future in the application of powdered metal parts is the automotive industry. Of particular concern in this field is the need to use powdered metal parts such as gears in more demanding applications such as power transmission applications. The problem with gears formed from powder metal processes is that powder metal gears have reduced bending fatigue strength in the tooth root region of the gear and the contact of the tooth flanks compared to gears formed from bar stock by machining or casting Reduced fatigue strength. These problems can be reduced or even eliminated by plastically deforming the root surface and flank regions through a process commonly referred to as surface densification. Products...

Claims

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Application Information

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IPC IPC(8): B22F3/00B22F3/087B22F3/10B22F3/17B22F3/24C22C33/02
CPCB22F3/1007B22F3/164B22F3/17B22F2998/00B22F2998/10B22F5/08B22F3/10B22F3/18
Inventor L·弗尔顿S·本特松
Owner HOGANAS AB
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