MX2008007520A - Copper-zinc alloy and synchronizing ring produced therefrom - Google Patents

Abstract

Copper-zinc alloy comprising from 55 to 75%by weight of copper, from 0.1 to 8%by weight of aluminium, from 0.3 to 3.5%by weight of iron, from 0.5 to 8%by weight of manganese, from 0 to less than 5%by weight of nickel, from 0 to less than 0.1%by weight of lead, from 0 to 3%by weight of tin, from 0.3 to 5%by weight of silicon, from 0 to less than 0.1%by weight of cobalt, from 0 to less than 0.05%by weight of titanium, from 0 to less than 0.02%of phosphorus, unavoidable impurities and zinc as balance.

Description

- - ALLOY OF COPPER-ZINC AND SYNCHRONIZATION RING PRODUCED FROM THE SAME DESCRIPTION OF THE INVENTION The invention relates to a copper-zinc alloy which is essentially lead-free. The invention also relates to a use of said copper-zinc alloy to produce a synchronizer ring as well as for a synchronizer ring. Copper-zinc or bronze alloys are used in the healthcare industry as well as in the electronics industry. In the automotive industry, bronze rings with high wear resistance and a high coefficient of friction are used for synchronizing rings which are used in a mechanical gearbox to synchronize the gear wheel. In order to be able to easily process the copper-zinc alloy, particularly by machining, a certain brittle condition of the material must be obtained in order to avoid as much as long chips can be created during processing which can be difficult to transport. eliminating it from the workplace and the processing tool. As is known, this desired brittle condition for mechanical bronze processing is obtained by adding a certain proportion of lead.

- - However, the lead in corresponding dose represents in a disadvantageous manner a danger to human health. Therefore, it is desirable to provide mechanically processable copper-zinc alloys which have a lead content as low as possible or even zero. Although several European Union line guides still allow the use of lead in bronze alloys, it should nevertheless be expected that a lead content of up to 4% allowed for bronzes used in motor vehicles will be corrected to decrease. A lead-free copper-zinc alloy for applications in the sanitary industry is known from EP 1 045 041 Bl. The described alloy comprises 69 to 79% by weight of copper, 2 to 4% by weight of silicon, 0.1 to 1.5% by weight of aluminum and 0.02 to 0.25% by weight of phosphorus. This interaction of the components of silicon, aluminum and phosphorus is intended to produce a phase? of the alloy which ensures a good processability of machining without using lead. Finally, DE 38 09 994 C3 forms a copper-zinc alloy for a synchronizer ring of 20 to 40% by weight of zinc, 2 to 8% by weight of aluminum, from at least two additional components which form intermetallic compounds, at least one of the components is titanium and for the remnant part of copper and random impurities. The high wear resistance is obtained by the intermetallic compounds. Lead is unnecessary. A common feature of lead-zinc copper alloys low in lead and lead-free which have a high resistance to wear is that they have a high content of intermetallic phases. These intermetallic phases generate some brittle condition of the alloy so that the machining process becomes easier. The chips are easily broken and can be transported by eliminating. For this reason, the proportion of lead can be reduced or lead can be omitted. If high wear resistance is not required as in EP 1 045 041 Bl, then the content of lead can be reduced by stabilizing a phase and in the alloy through an interaction of silicon, aluminum and phosphorus. This alloy contains phosphorus in order to ensure a resistance to the desalting of the alloy for the desired application in the sanitary industry. An object of the invention is to provide a copper-zinc alloy with maximum wear resistance, in particular, it is suitable for use in a synchronizer ring and is essentially lead-free. This object is obtained according to the invention by a copper-zinc alloy which comprises 55 to 75% by weight of copper, 0.1 to 8% by weight of aluminum, 0.3 to 3.5% by weight of iron, 0.5 to 8% by weight of manganese, 0 to less than 5% by weight of nickel, 0 to less than 0.1% by weight of lead, 0 to 3% by weight of tin, 0.3 to 5% by weight of silicon, 0 to less than 0.1% by weight of cobalt, 0 to less than 0.05% by weight of titanium, 0 to less than 0.02% by weight of phosphorus, unavoidable impurities and the rest of zinc. The invention is based on the idea of deliberately lowering the lead content below 0.1% by weight without providing compensation with respect to the mechanical processing capacity desired by intermetallic phases or stabilization of a phase? Sufficient wear resistance is ensured by the necessary alloying components aluminum, manganese, iron and silicon. Manganese, iron and silicon in the specified quantitative ranges generate a sufficient basic proportion of intermetallic phases in the copper-zinc alloy. In particular, aluminum hardens mixed glass. Manganese makes a positive contribution to wear resistance. An improvement can be obtained by the additional alloying components optionally mentioned nickel and tin. It can contain cobalt and titanium up to below the specified limits. The alloy with these surpassed materials, however, is unnecessary for the capacity - - of desired mechanical processing and to obtain the wear resistance that is desired. Phosphorus as an alloying component is unnecessary to improve the resistance to dezincification. The decrease in the lead content below 0.1% by weight without increasing the proportion of intermetallic phases is surprisingly possible, contrary to the previous opinion of the technical world since it has been found that after extensive studies, it is possible to machine the copper alloy -Zinc that is claimed, particularly to produce a synchronizer ring even without adding lead. The wear resistance and the abrasion resistance of the copper-zinc alloy can be improved when the copper-zinc alloy advantageously comprises aluminum in a proportion of 0.5 to 2.5% by weight, iron in a proportion of 0.3 to 1% by weight, manganese in a proportion of 0.5 to 5% by weight, nickel in a proportion of 0.5 to less than 5% by weight, tin in a proportion of 0 to 1.5% by weight and silicon in a proportion of 0.3 to 2% in weigh. In an alternative advantageous embodiment of the invention, the copper-zinc alloy comprises a greater proportion of aluminum and is distinguished in that it comprises aluminum in a proportion of 3 to 8% by weight, iron in a proportion of 1 to 3% by weight , manganese in - - a proportion of 5 to 8% by weight, nickel in a proportion of 0 to less than 0.5% by weight, tin in a proportion of 0 to less than 0.5% by weight and silicon in a proportion of 1 to 4% by weight weight. Said material has the necessary mechanical properties for a synchronizing ring. The copper-zinc alloy is suitable for producing a synchronizing ring, particularly by machining. The exemplary embodiments of the invention will be explained in more detail with the aid of the drawing and the following examples. Figure 1 shows a synchronizer ring in a perspective representation. Figure 1 represents a typical synchronizer ring as can be produced in particular by machining from a copper-zinc alloy. The synchronizer ring 1 has an internal surface 3 which is designed for friction pairing with a conical friction partner. The teeth 2, which engage with corresponding grooves in a matching grooved sleeve, are distributed on the outer circumference of the synchronizer ring 1. In order to improve the oil output, the internal surface 3 has oil channels 4 placed in an axial direction which quickly transport away the oil present in the oil. case of friction matching.

EXAMPLES A total of four alloys were studied, each pair of alloys differing only in their lead content. Alloy 1A contains 57.9% by weight of copper, 1.65% by weight of aluminum, 0.4% by weight of iron, 1.95% by weight of manganese, 0.55% by weight of lead, 0.6% by weight of silicon and the rest of zinc . The alloy IB differs from this alloy 1A in that the lead is absent from it, ie it contains lead only as an unavoidable impurity concentration of 0.02% by weight. Alloy 2A contains 69.7% by weight of copper, 5.2% by weight of aluminum, 1.1% by weight of iron, 7.8% by weight of manganese, 0.8% by weight of lead, 1.8% by weight of silicon and the rest of zinc as well as unavoidable impurities. Alloy 2B differs from the 2A alloy in that it contains lead only at an unavoidable concentration of 0.05. The alloys A are lead-containing comparative alloys which are suitable with respect to their wear resistance and susceptibility to processing for synchronizing rings. The B alloys are embodiments of the invention.

Example 1: For these alloys, the wear resistance in km / g and the coefficient of friction are determined in the friction and wear balance of Reichert with a sliding speed of 1.65 m / sec and a load of 52 N / mm2 over a total displaced distance of 2500 m For this purpose, a bronze bolt made of the respective test alloy with a diameter of 2.7 mm is pressed with the specified load onto a rotating steel ring. In the wear resistance and the coefficient of friction are determined from the weight loss of the bronze bolt after a specified distance of shifting. The result is summarized in the following table: It can be seen that the wear resistance and the coefficient of friction of the lead-free B alloys are not inferior in relation to the lead-containing A alloys, but on the contrary they have increased.

- - Example 2: Cutting tests with said alloys are carried out. For this purpose, a screwed thread with a thread depth of 0.37 mm, a pitch of 0.65 mm and a flank angle of 60 ° is cut in synchronizer rings according to figure 1, which are made from the alloys of proof. The threaded groove runs five times in total; that is, five threading sausages are made. A K20 grade carbide material according to DIN 4990 is used as the thread cutting material. After a defined number of cutting grooves cut into the cutting tool, the wear of the tool is measured. For this purpose, the difference in the cross-sectional area of the threading step before and after carrying out the test is determined. The following results are obtained: The test is stopped after 6848 threaded grooves for the alloy 1A since there has been significant wear of the tool there. It can be established that wear of the tool with lead-free B alloys shows less wear than lead-containing A-alloys.

Example 3: The separated chips are observed in the cutting tests carried out according to Example 2. It is established that although the chip of the lead-free B alloys are longer compared to the alloys A containing lead, it is not they form in such a way that they intertwine and tangle together. Contrary to what is expected, the chips are transported eliminating without problems during the machining. Lead-free alloys are particularly suitable for producing a synchronizer ring. Therefore, the addition of lead can be eliminated to improve the susceptibility to mechanical processing. LIST OF REFERENCES 1 synchronizer ring 2 teeth 3 internal surface 4 oil channels

Claims (3)

1. CLAIMS 1. Copper-zinc alloy comprising 55 to 75% by weight of copper, 0.1 to 8% by weight of aluminum, 0.3 to 3.5% by weight of iron, 0.5 to 8% by weight of manganese, 0 to less than 5% by weight of nickel, 0 to less than 0.1% by weight of lead, 0 to 3% by weight of tin, 0.3 to 5% by weight of silicon, 0 to less than 0.1% by weight of cobalt, 0 to less 0.05% by weight of titanium, 0 to less than 0.02% by weight of phosphorus, unavoidable impurities and the rest of zinc. 2. Copper-zinc alloy as described in claim 1, characterized in that it comprises aluminum in a proportion of 0.5 to
2. 2.5% by weight, iron in a proportion of 0.3 to 1% by weight, manganese in a proportion of 0.5 to 5 % by weight, nickel in a proportion of 0.5 to less than 5% by weight, tin in a proportion of 0 to 1.5% by weight and silicon in a proportion of 0.3 to 2% by weight. 3. Copper-zinc alloy as described in claim 1, characterized in that it comprises aluminum in a proportion of 3 to 8% by weight, iron in a proportion of 1 to 3% by weight, manganese in a proportion of 5 to 8. % by weight, nickel in a proportion of 0 to less than 0.5% by weight, tin in a proportion of 0 to less than 0.5% by weight and silicon in a proportion of 1 to 4% by weight. 4. Use of a copper-zinc alloy as described described in one of claims 1 to 3 to produce a synchronizer ring. Use as described in claim 4, characterized in that the synchronizing ring seeks to start from the copper-zinc alloy by machining. 6. Synchronizer ring made of a copper-zinc alloy, according to claims 1 to
3. 3.