EP1980633B1 - Use of a bronze alloy for a worm gear - Google Patents

Abstract

Copper alloys for the production of semi-finished and finished components by continuous casting and subsequent machining have the following composition (wt%): copper 84.5 - 87.5; tin 11.0 - 13.0; nickel 1.5 - 2.5; lead below 0.3; phosphorus 0.05 - 0.4; and zirconium 0.04 - 0.25. They also contain a maximum of 0.5% in total of additional components comprising antimony 0.10% max; sulfur 0.05% max; and zinc 0.40% max. An independent claim is included for production of semi-finished and finished components by continuous casting and subsequent machining in which the P and Zr contents of the copper melt are produced using P-Cu pre-alloys containing 10% of P and 90% of Cu and Zr-Cu prealloys containing 33% of Zr and 67% of Cu.

Description

The invention relates to the use of a copper-tin-based copper alloy for the production of worm gears of worm gear drives by continuous casting and subsequent mechanical processing. Moreover, the invention relates to a method for producing a semifinished product or component from a copper-tin-based copper alloy, wherein the copper alloy is continuously cast, then the strand sawn and made of the strand pieces by machining a semifinished product or a finished component.

In general, there is a trend that components of a mechanical drive, such as gear parts, are exposed to ever higher loads. This also applies, for example, to worm gears, which are playing an increasingly important role in drive technology. In worm gears, the worm wheel is often made of a copper-tin-based copper alloy, that is, a bronze alloy, in order to achieve good sliding properties of the worm wheel and thus to provide a low-noise worm gear. Low noise results from a high proportion of Gleitwälzbewegungen, with high sliding velocities with relatively high flank pressure presupposing material combinations suitable for use. This is achieved for example by a hard-soft combination of materials. Since the case hardened steel screw and the worm wheel are copper-tin-based copper alloy, the worm wheel made of bronze limits the transmission life due to wear thereof. In principle, the Gear life can be increased by the use of steel or gray cast iron as Scheckenradwerkstoff. However, this is often accompanied by deteriorated inlet characteristics and higher noise levels.

From the European patent application EP 749 897 A1 Copper-tin alloys for the production of water-bearing castings are known, which show a low migration tendency of the alloying constituents in the water to be led.

From the EP 0 926 251 A1 Further, copper-tin-titanium alloys are known, which are used for the production of worm wheels of worm gear.

On this basis, it is an object of the present invention to propose the use of a copper-tin-based copper alloy, which allows the production of components, such as worm wheels, with a longer service life and low noise of the transmission. In addition, the invention has the object to provide a method for producing semi-finished or finished components of a corresponding copper alloy.

$$1,50\%\le \mathrm{Ni}\le 2,50\%,$$

$$\mathrm{Pb}\le 0,30\%,$$

$$\mathrm{0}\mathrm{,}\mathrm{05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0}\mathrm{,}\mathrm{40}\mathrm{\%}\mathrm{,}$$

$$0,04\%\le \mathrm{Zr}\le 0,25\%,$$

$$84,5\%\le \mathrm{Cu}\le 87,5\%,$$

maximal in Summe 0,5 % der folgenden
Legierungsbestandteile, wobei die
Legierungsbestandteile einzeln die folgenden Gehalte aufweisen: $$\mathrm{Sb}\le 0,10\%,$$

$$\mathrm{S}\mathrm{\le }\mathrm{0}\mathrm{,}\mathrm{05}\mathrm{\%}\mathrm{,}$$

$$\mathrm{Zn}\le 0,40\%$$

und unvermeidbare Verunreinigungen.The above object is achieved, according to a first teaching of the present invention, by using a copper-tin-based copper alloy for producing worm wheels of worm gears in that the copper alloy has the following alloy components in% by weight: $$11.0\%\le \mathrm{sn}\le 13.0\%.$$

$$1.50\%\le \mathrm{Ni}\le 2.50\%.$$

$$\mathrm{pb}\le 0.30\%.$$

$$\mathrm{0}\mathrm{.}\mathrm{05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0}\mathrm{.}\mathrm{40}\mathrm{\%}\mathrm{.}$$

$$0.04\%\le \mathrm{Zr}\le 0.25\%.$$

$$84.5\%\le \mathrm{Cu}\le 87.5\%.$$

a maximum of 0.5% of the following
Alloy components, wherein the
Alloy components individually have the following contents: $$\mathrm{sb}\le 0.10\%.$$

$$\mathrm{S}\mathrm{\le }\mathrm{0}\mathrm{.}\mathrm{05}\mathrm{\%}\mathrm{.}$$

$$\mathrm{Zn}\le 0.40\%$$

and unavoidable impurities.

The Sn content of the copper alloy according to the invention leads to finely divided, very hard and Sn-rich microstructural constituents, which contribute significantly to increasing the wear resistance. In addition, the Sn content enables an improvement in the toughness properties of the copper alloy according to the invention to be achieved via a heat treatment. In addition, a strength and hardness increase is achieved via the nickel content of 1.5 to 2.5% by weight, without adversely affecting the machinability. The relatively low lead content of less than 0.3 wt .-% ensures that only small amounts of lead are released in the abrasion. The phosphorus content of 0.05% by weight to 0.40% by weight improves the castability of the copper alloy according to the invention in the continuous casting process. About that In addition, the addition of zirconium in a proportion of 0.04 wt .-% to 0.25 wt .-% in conjunction with the other alloying constituents ensures that also during the continuous casting of the copper alloy, a particularly fine microstructure, resulting in significantly improved properties of the invention Copper alloy leads. Finally, the copper alloy according to the invention comprises 84.5% to 87.5% copper. Limiting the contents of antimony, sulfur and zinc to a total of no more than 0.5% by weight, the upper limits for antimony being 0.10% by weight, for sulfur being 0.05% by weight and for zinc 0, 40 wt .-%, ensures that the improved wear properties of the copper alloy according to the invention are not deteriorated.

$$2,0\%\le \mathrm{Ni}\le 2,20\%,$$

$$0,05\%\le \mathrm{Pb}\le 0,30\%,$$

$$\mathrm{0}\mathrm{,}\mathrm{05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0}\mathrm{,}\mathrm{20}\mathrm{\%}\mathrm{,}$$

$$0,05\%\le \mathrm{Zr}\le 0,20\%$$

und $$85,5\%\le \mathrm{Cu}\le 86,85\%\mathrm{.}$$

With regard to the wear resistance, the use according to the invention of the copper alloy according to a first embodiment can be further improved in that the copper alloy additionally has the following alloy constituents in% by weight: $$11.0\%\le \mathrm{sn}\le 11.\mathrm{8th}\%.$$

$$2.0\%\le \mathrm{Ni}\le 2.20\%.$$

$$0.05\%\le \mathrm{pb}\le 0.30\%.$$

$$\mathrm{0}\mathrm{.}\mathrm{05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0}\mathrm{.}\mathrm{20}\mathrm{\%}\mathrm{.}$$

$$0.05\%\le \mathrm{Zr}\le 0.20\%$$

and $$85.5\%\le \mathrm{Cu}\le 86.85\%\mathrm{,}$$

The combination of the abovementioned alloy constituents in their precisely matched quantities ensures an even finer microstructure of the copper alloy after continuous casting, so that the wear properties are improved despite good processability of the cast strands.

According to a second teaching of the present invention, the above-described object is achieved by a generic method for producing a component from a copper alloy according to the invention in that before casting the content of the copper melt of phosphorus and zirconium by alloying zirconium-copper and phosphorus-copper Alloying the zirconium with a Zr-Cu master alloy with 67% Cu and 33% Zr content and the addition of phosphorus with a P-Cu master alloy with 90% Cu and 10% P-share is done.

The specified master alloys allow a particularly accurate adjustment of the contents of zirconium and phosphorus in the copper alloy according to the invention and thus allow precise control of the microstructure.

A particularly economical method for producing a component from a copper alloy according to the invention results according to a next embodiment of the method according to the invention in that the removal speed during continuous casting is greater than 50 mm / min, preferably greater than 80 mm / min. Although the peel rate depends on the diameter of the strand and therefore the amount of metal to be cooled, with the copper alloy according to the invention, however, an increase in the peel rates of copper-tin-based copper alloy could be achieved without having to compromise on the structural quality. Despite the high Withdrawal speeds, a microstructure with a grain size of around 60 μm is achieved.

Preferably, solid rods or tubes up to a diameter of 200 mm, preferably 180 mm are produced by the continuous casting. These dimensions allow for sufficient peel-off speed and allow the production of finished blanks from sawn blanks without the need for very large amounts of waste. The tubes can have both a circular cross section and a square, hexagon or a polygonal cross section.

Finally, according to a next embodiment of the method according to the invention, worm wheels of a worm gear or semifinished products for the production of worm wheels are produced by worm gears. Worm wheels of a worm gear made from the copper alloy according to the invention are not only quiet in their use in drive technology, but also have a particularly good wear resistance. This leads directly to an extension of the life of the equipped with the corresponding worm gears drives.

There are now a variety of ways to develop the copper alloy according to the invention and the inventive method for producing a component of a copper alloy according to the invention and to design. Reference is made on the one hand to the claims subordinate to claims 1 and 3 and to the description of an embodiment.

$$2,0\%\le \mathrm{Ni}\le 2,20\%,$$

$$0,05\%\le \mathrm{Pb}\le 0,30\%,$$

$$\mathrm{0}\mathrm{,}\mathrm{05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0}\mathrm{,}\mathrm{20}\mathrm{\%}\mathrm{,}$$

$$0,05\%\le \mathrm{Zr}\le 0,20\%$$

und $$85,5\%\le \mathrm{Cu}\le 86,85\%\mathrm{.}$$

In the exemplary embodiment, first of all a copper alloy has been produced, which has the following alloy constituents in% by weight: $$11.0\%\le \mathrm{sn}\le 11.80\%.$$

$$2.0\%\le \mathrm{Ni}\le 2.20\%.$$

$$0.05\%\le \mathrm{pb}\le 0.30\%.$$

$$\mathrm{0}\mathrm{.}\mathrm{05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0}\mathrm{.}\mathrm{20}\mathrm{\%}\mathrm{.}$$

$$0.05\%\le \mathrm{Zr}\le 0.20\%$$

and $$85.5\%\le \mathrm{Cu}\le 86.85\%\mathrm{,}$$

The copper alloy was continuously cast at a casting temperature of 1150 ° C to 1250 ° C in a graphite mold. With a peel rate of about 85 mm / min. a pipe was drawn with an outer diameter of 120 mm and an inner diameter of 70 mm. Subsequently, the continuously cast pipe was sawed into pieces of strands and further processed into semi-finished products for the production of worm wheels. It was found that the worm wheels produced from the copper-tin-based copper alloy according to the invention were particularly wear-resistant and nevertheless have the good running-in properties of conventional worm wheels made of conventional copper-tin-based copper alloys. In a structural investigation, it was found that the grain sizes were in the range of 60 microns and are similar to the centrifugal casting evenly from α-substitution crystals together with δ phases embedded in the grain boundaries. It is assumed that this microstructure is responsible for the good shrinkage properties and wear properties. In particular, with the copper alloy according to the invention, compared to the known copper alloy CuSn12Ni according to DIN standard DIN EN 1982, approximately 15% improved values with regard to the tensile strength RP0.2 and the elongation A _{5 were} achieved. This improvement in mechanical properties is due in particular to the optimized microstructure. As a result, a much longer service life of a worm wheel sets in.

Claims (7)

1. Use of a copper alloy based on copper-tin for producing worm wheels of worm drives by continuous casting and subsequent machining, characterised in that the copper alloy has the following alloying elements in % wt.: $$11.0\%\le \mathrm{Sn}\le 13.0\%,$$

   

   $$1.5\%\le \mathrm{Ni}\le 2.5\%,$$

   

   $$\mathrm{Pb}\le 0.3\%,$$

   

   $$\mathrm{0.05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0.4}\mathrm{\%}\mathrm{,}$$

   

   $$0.04\%\le \mathrm{Zr}\le 0.25\%,$$

   

   $$84.5\%\le \mathrm{Cu}\le 87.5\%,$$

   

   
   a maximum in total of 0.5 % of the following alloying elements, wherein these alloying elements individually have the following contents: $$\mathrm{Sb}\le 0.10\%,$$

   

   $$\mathrm{S}\mathrm{\le }\mathrm{0.05}\mathrm{\%}\mathrm{,}$$

   

   $$\mathrm{Zn}\le 0.40\%$$

   

   and unavoidable impurities.
2. Use according to Claim 1, characterised in that the copper alloy has the following alloying elements in % wt.: $$11.0\%\le \mathrm{Sn}\le 11.8\%,$$

   

   $$2.0\%\le \mathrm{Ni}\le 2.20\%,$$

   

   $$0.05\%\le \mathrm{Pb}\le 0.30\%,$$

   

   $$0.05\%\le \mathrm{P}\le 0.20\%,$$

   

   $$0.05\%\le \mathrm{Zr}\le 0.20\%$$

   

   and $$85.5\%\le \mathrm{Cu}\le 86.85\%\mathrm{.}$$

   
3. Method for producing a semi-finished product or component from a copper alloy based on copper-tin, wherein the copper alloy has the following alloying elements in % wt.: $$11.0\%\le \mathrm{Sn}\le 13.0\%,$$

   

   $$1.5\%\le \mathrm{Ni}\le 2.5\%,$$

   

   $$\mathrm{Pb}\le 0.3\%,$$

   

   $$\mathrm{0.05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0.4}\mathrm{\%}\mathrm{,}$$

   

   $$0.04\%\le \mathrm{Zr}\le 0.25\%,$$

   

   $$84.5\%\le \mathrm{Cu}\le 87.5\%,$$

   

   
   a maximum in total of 0.5 % of the following alloying elements, wherein these alloying elements individually have the following contents: $$\mathrm{Sb}\le 0.10\%,$$

   

   $$\mathrm{S}\mathrm{\le }\mathrm{0.05}\mathrm{\%}\mathrm{,}$$

   

   $$\mathrm{Zn}\le 0.40\%$$

   

   
   and unavoidable impurities,
   wherein the copper alloy is continuously cast, then the strand is sawn and the semi-finished product or component is produced from the strand pieces by cutting processes,
   characterised in that before continuous casting takes place the content of phosphorus and zirconium in the copper melt is set by adding phosphorus-copper (P-Cu) and zirconium-copper (Zr-Cu) pre-alloys by alloying, wherein the zirconium is added by alloying using a Zr-Cu pre-alloy with a 67 % proportion of Cu and a 33 % proportion of Zr and the phosphorus is added by alloying using a P-Cu pre-alloy with a 90 % proportion of Cu and a 10 % proportion of P.
4. Method according to Claim 3, characterised in that the pulling rate during continuous casting is greater than 50 mm/min, preferably greater than 80 mm/min.
5. Method according to Claim 3 or 4, characterised in that solid bars or tubes up to a diameter of 200 mm, preferably 180 mm, are produced by the continuous casting process.
6. Method according to any one of Claims 3 to 5, characterised in that worm wheels of a worm drive or semi-finished products for producing worm wheels of worm drives are produced.
7. Method according to any one of Claims 3 to 6, characterised in that the copper alloy additionally has the following alloying elements in % wt.: $$11.0\%\le \mathrm{Sn}\le 11.8\%,$$

   

   $$2.0\%\le \mathrm{Ni}\le 2.20\%,$$

   

   $$0.05\%\le \mathrm{Pb}\le 0.30\%,$$

   

   $$\mathrm{0.05}\mathrm{\%}\mathrm{\le }\mathrm{P}\mathrm{\le }\mathrm{0.20}\mathrm{\%}\mathrm{,}$$

   

   $$0.05\%\le \mathrm{Zr}\le 0.20\%$$

   

   and $$85.5\%\le \mathrm{Cu}\le 86.85\%\mathrm{.}$$