CS256724B1 - A method of producing copper pipes for refrigeration purposes - Google Patents

Abstract

The pins cast from the melt, cooled from a temperature of 1150 to 1180 °C at a rate of 30 to ΘΟθΟ.δ”1, are heated to a temperature of 820 to 860 degrees Celsius. Then, tubes with a wall thickness of max. 3 mm are pressed from them. These are drawn by gradual drawing to a thickness of 0.75 mm with a reduction for individual draws of 20 to 31% and below a thickness of 0.75 mm with a reduction of 15 to 25 percent. The finished tubes are annealed to a shine at a temperature of 450 to 480 °C for 0.5 to 2 hours.

Description

256724

The invention solves the method of producing copper coins for refrigerated purposes.

A known method of producing tubes for refrigeration purposes consists in casting pins from a zinc-oxidized medium; which heats up to 920 to 950 ° C, and pipes up to 3 mm thick. The pipes thus extruded are cut into respective lengths and are drawn sequentially on single-strand or multi-strand pulling stools. The emulsion fat is used as a lubricant, both pre-internal and external for lubrication. The finished tubes are annealed in a protective atmosphere at a temperature of 560 to 600 ° C for 2 to 4 hours. The disadvantage of this technique is that the pipes thus produced do not have the phosphorus content guaranteed, ie they are not resistant to oxidation-reduction annealing (the formation of non-tightness of the material), they do not have a satisfactory purity of both the inner and outer surface due to the unsuitable type ma-zadla, and have unsatisfactory mechanical properties for more flawless technological processing such as bending, widening.

The above drawbacks are overcome by the process of producing copper tubes for refrigeration purposes according to the invention, the principle of which is to melt the castings cooled from 1150 to 1180 [deg.] C. with a melt speed of 30 to 90 [deg.] C. s_1 are heated to a temperature of 820-860 ° C and then the tubes are pressed with a wall thickness of max. 3 mm. These are then pulled by gradual pulling to a depth of 0.75 mm, with a reduction to individual strokes of 20 to 31% and below a pitch of 0.75 mm with a reduction of 15 to 25%. The finished tubes are bronzed. The present invention is based on the fact that the annealing is performed at a temperature of 450 to 480 ° C for 0.5 to 2 hours. The invention is also based on the fact that, in individual strokes, the inner surface of the tubes is lubricated with a viscosity of 16.7 mm 2. s1 at 60 ° C and melting point 37 to 58 ° C. The outer surface is lubricated with a lubricant having a viscosity of 21 to 30 mm 2. with "1 at 20 ° C, density at 20 ° Cmin. 0.845 g. cm 3, flash point in the crucible at least 140 ° C, solidification max. -5 ° C, acid value max.0.02 mg. KOH Advantages of the process according to the invention are that the tubes made according to the invention combine qualitatively the requirements imposed on them from the inner surface, the mechanical properties and the dimensions.

Semi-continuous casting pins of 245 mm diameter were cast. The casting temperature was 1160 ° C, the casting speed was 13 cm. min "1, cooling water quantity 360 to 380 microns" 1. Heating pins 0 245 x 450 mm by pre-pressing to 830 ° C and pressed tube 50 x 3 mm into water followed by coiling. Pulling was carried out by a loading drum of diameter D = 1600 mm by the following procedure: pull: Dxt (mm) Re (%) Rd (%) Rt (%) 1. 42.5 x 2.60 26.43 15.11 13.33 2. 36.70 x 2.10 29.96 13.28 19.23 3. 31.80 x 1.70 29.58 13.01 19.05 4. 27.80 x 1.35 30.22 12, 13 20.59 5. 24.40 x 1.10 28; 22 11.91 18.52 6. 21.50 x 0.90 27.66 11.59. 18.18 7. 19.00 x 0.75 26.17 11.41 16.67 8. 16 90 x 0.65 22.83 10.96 13.33 9. 15.00 x 0.55 24.76 11.08 15.38 10. 13.00 x 0.50 21.36 13.49 9) 09 11. 11.30 x 0.45 21.88 13.20 10.00 12. 9.53 x 0.4 25 , 24 15.90 11.11 where:

Rc - total reductionR (i - reduction to diameterRt - reduction to the wall ridge In all tensions, the inner surface was lubricated with a viscosity of 16.7mm2.s4 at 60 ° C and a melting point of 37-58 ° C. at 20 ° C, density at 20 ° C min 0.845 g cm -1, flare point in open crucible min.140 ° C, pour point max - 5 ° C, max. 0.02 mg KOH, g "1 and a content of max.

After the last stroke, the tubes were annealed in a continuous furnace with a protective atmosphere of 450 ° C for 2 hours. The tubes produced by the process of the invention all meet the conditions for their use in the production of high quality refrigeration units. The mechanical properties were as follows:

Claims (3)

2 5 6 7 2 4 5 yield strength Rp02 = 80 to 100 MPa, tensile strength R, n = 240 to 270 MPa, ductility of Aiomin - 40% and grain size according to step 3. 6 The inner surface contained up to 20 mg . m ~ 2 mechanical impurities and up to 60 mg .. m 2 of oil residues. object A process for the production of copper tubes for the purpose of refining, characterized in that the melt-molded parts are cooled from 1150 to 1180 ° C at a rate of 30 to 90 ° C. . s1 is heated to a temperature of 820 to 860 ° C and thereafter compressed tubes with a thickness of at most 3 mm, which are pulled by successively pulling to a depth of 0.75 mm with reduction to individual strokes of 20 to 31% and 0.75 mm undergrowth with a reduction of 15 to 25 ° / o, with the finished tubes glowing. 2. A process according to claim 1, characterized in that the gloss treatment is carried out at a temperature of 450 to 480 ° C for 0.5 to 2 hours. THE INVENTION 3. A process according to claim 1, characterized in that the inner surface of the tubes is lubricated with a viscosity of 16.7 mm2 for each tube. with an external surface having a lubricant having a viscosity of 21 to 30 mm 2. with * 1 at 20 ° C, density at 20 ° C at least 0.845grams. cm-3, a flash point in the open crucible of at least 140 ° C, a solidification point of at most -5 ° C, an acid number of at least 0.02 mg KOH. g'1 and a content of at most 0.01 wt.