DE1752672A1 - Process for the manufacture of assembled parts - Google Patents

Description

The invention relates to a process for the production of composite parts consisting of at least two pieces which must have different and often mismatched mechanical properties, such as excellent machinability and increased toughness on the one hand and excellent wear resistance on the other .

To achieve composite parts of this type it is known to use a cast insert and to surface treat the part by induction or flame. However, this surface treatment is generally very difficult because of the desired delimitation of the zone to be treated.

The invention relates to a method of manufacturing assembled parts which, on the contrary, is easy to carry out.

The inventive method consists in the manufacture of a first piece of spheroidal graphite cast iron and the

Manufacture of a second piece from self-hardening casting, one part being poured into or onto the other part and the piece consisting of the two parts being subjected to a thermal treatment.

The method according to the invention can be used every time a piece is to be obtained, the two parts of which do not have to have mutually compatible properties, such as the shift fork of a gearbox. However, the method is particularly suitable for the production of rocker arms that are used in engines with a high speed range, in particular in the camshafts of these engines.

The manufacture of the rocker arm shown in the drawing, which must have an easily machinable body 1 and a shoe insert with high wear resistance, can be effected in accordance with the following description.

The shoe insert 2 is produced from casting in a lost wax mold, the melt having the following compositions:

Melt A Melt B Melt C Melt D Melt E

C 3.0-3.20% 3.0-3.20% 3.0-3.20% 3.0-3.20% 3.0-3.20%

Si 1.9-2.20% 1.9-2.20% 1.9-2.20% 1.9-2.20% 1.9-2.20%

Mn 0.70-0.90% 0.70-0.90% 0.70-0.90% 0.70-0.90% 0.70-0.90%

Cr 1.10-1.30% 0.60-0.80% 1.10-1.30% 1.10-1.30% 1.10-1.30%

Mon 0.30-0.80% 0.30-0.80% - 0.30-0.80% 0.30-0.80%

Cu 1 -1.6% - - 0.60-1.20% -

Ni - 1 -1.6% 1.4-1.6% 0.3-0.8% 1 -1.6%

B - 0.10% - - -

W - - 0.6-1.8% - -

P <0.20% <0.20% <0.20% <0.20% <0.20%

S <0.10% <0.10% <0.10% <0.10% <0.10%

The content of carbon and silicon in the melt is changed in such a way that an alternating laminar structure of carbide and graphite is created. The shoe insert 2 has a tail 3 which is fastened in an anchoring opening 4. The piece of shoe is then inserted into a mold with which part 1 is manufactured, whereupon a spheroidal graphite cast iron melt at a temperature of 1400 to 1450 ° C is poured into this casting mold, which has the following composition, for example:

C = 3.3-3.8% Si = 2.0-3.0% Mn = 0.4-0.8%

The raw casting is then treated according to the normal, classical process, which consists of heating to 900 ° + -20 ° C for 1 to 2 hours and cooling in the furnace to around 800 ° C + -20 ° C, the casting at this temperature held for about 15 minutes and then exposed to calm or moving air.

Part 1 of the rocker arm has a lower or even hardness of 100 HR [deep] B, while the shoe insert 2 has an upper hardness of about 55 to 56 HR [deep] C.

The invention also aims at assembled pieces as new industrial products, in particular rocker arms for camshafts, which can be manufactured by the method described above.

The invention is not restricted to the exemplary embodiment, but rather encompasses all of its modification forms.

Claims (2)

1. A method for producing an assembled piece consisting of an easily machinable part and a part with excellent wear resistance, characterized in that the one part that must be easily machinable is made from a spheroidal graphite cast iron melt that contains 3.3% to 3 , 8% carbon, 2.0% to 3.0% silicon and 0.4 to 0.8% manganese, and the other part, which must have excellent wear resistance, is made from a self-hardening cast melt that is 3.0 contains up to 3.2% carbon, 1.9% to 2.2% silicon, 0.7% to 0.9% manganese, at most 0.2% phosphorus, at most 0.1% sulfur and additionally contains either 1.1% to 1.3% chromium, 0.3% to 0.8% molybdenum, and 1.0% to 1.6% copper or 0.6% to 0.8% chromium, 0.3% to 0.8% molybdenum, 1.0% to 1.6% nickel and noticeably 0.1% boron or 1.1% to 1.3% chromium, 1.4 to 1.6% nickel and 0.6% to 1.8% tungsten or 1.1% to 1.3% chromium, 0.3% to 0.8% molybdenum, 0.6% to 1.2% copper and 0.3% to 0.8% nickel or 1.1% to 1.3% chromium, 0.3% to 0.8% molybdenum and 1.0% to 1.6% nickel, and that the entire piece consisting of the parts is subjected to a treatment which consists of 1 to 2 hours heating to 900 ° C + -20 ° C, cooling to about 800 ° C + -20 ° C and that the piece kept at this temperature and exposed to air. 2. Assembled piece, in particular an angle lever for the camshaft of an engine, characterized in that the angle lever is produced by the method characterized in claim 1.