The method of producing on a hydraulic press the forging of the AZ31 magnesium alloy wheel for light vehicles and the forging of the wheel produced according to the method

Abstract

The subject of the invention is a method of manufacturing a magnesium alloy wheel forging on a hydraulic press, characterized in that the upper die (1) having a working impression in the middle part (la) and the lower die (3) having a working impression (3a) in the form of a lump whose outline is similar to a circle with circular recesses in the middle, is heated in a furnace to a temperature of 260° C to 300 o C, after which a heated upper die (1) and a lower die (3) are mounted in the working space of a hydraulic press with a pressure of 1600 kN to 2242 kN, and then a forging preform (2a) in the form of a forging cast into metal forms of a magnesium alloy AZ31 (Mg-3Al-lZn) is heated in the furnace to a temperature of 350° C to 400° C, for a period of 40 to 45 minutes, after which the heated forging preform (2a) is placed in the working impression (3a) of the lower die (3), after which it is pressed with a hydraulic press on the upper die (1), causing the upper die (1) to move downwards with a velocity of 20 mm / s to 40 mm / s in the direction of the lower die (3), and the forging preform (2a) is crushed with the working impression (la) of the upper die (1) and the working impression (3a) of the lower die (3), shaping the forging (2b) of the wheels with a deformation in the range of 6.43 to 12.9. The object of the invention is also a wheel forging produced by the method as specified above.

Description

[0001] The method of producing on a hydraulic press the forging of the AZ31 magnesium alloy wheel for light vehicles and the forging of the wheel produced according to the method

[0002] The obj ect of the invention is a method for producing a magnesium alloy wheel forging AZ31 for light vehicles on a hydraulic press and a wheel forging produced according to the method .

[0003] The methods of manufacturing magnesium alloy wheels for light vehicles are known and used to date , such as , casting , machining , die forging .

[0004] For the generating of magnesium alloy wheels , the casting technology is used, which was described in the literature by K . E . Oczos , A. Kawalec "Shaping light metals" ( Polish : Ksztaltowanie metali lekkich ) , Wydawnictwo Naukowe PWN, Warsaw 2012 and A. A. Luo "Magnesium casting technology for structural applications" , Journal Magnesium Alloy, 2013 , vol . 1 , pp . 2-22 . The most commonly used types of magnesium alloy wheel casting are gravity casting , high pressure casting or low pressure casting . Due to the strong reactivity and the need for a protective atmosphere , magnesium alloy wheels are most often cast in the process of hot or cold chamber casting . This process helps obtain products with high properties .

[0005] Pressure die-casting offers attractive flexibility in the design and manufacture of magnesium wheels . Pressure diecasting of magnesium alloy wheels are designed with thin walls in areas where the product should not have high strength and with thicker walls in areas with higher strength requirements .

[0006] Non-pressure die-casting of magnesium wheels takes place in sand and metal moulds , by the full mould method or by the smelted models method . Non-pressure die-casting of magnesium wheels is rarely used due to the inferior mechanical properties of the castings , surface roughness and lower dimensional accuracy compared to the wheels obtained by the pressure casting method . Cast magnesium wheels are characterized by high dimensional accuracy and low production costs . Cast wheels have casting defects such as: heterogeneity of structure, coarse grain, blisters, porosity, shrinkage cavities, rust, which affect their lower properties compared to those obtained by plastic processing methods .

[0007] When generating magnesium alloy wheels, the machining technology is used, which is described in W. Olszak's literature "Machining", Wnt, Warsaw 2008. The machining of magnesium alloy wheels consists in giving the surfaces the desired shape, dimensions and surface quality by removing the material from the impression in the form of a roller using cutting tools. This method is labor-intensive, time-consuming and energy-intensive. During the machining process of magnesium wheels, large material losses are generated, and the quality of the obtained products is lower than that obtained by plastic processing methods.

[0008] The best mechanical and functional properties of magnesium alloy wheels for light vehicles are ensured by the plastic processing processes described in the literature by K. E. Oczos, A.Kawalec "Shaping light metals", Wydawnictwo Naukowe PWN, Warsaw 2012 and J. Sihczak "Processes of plastic processing", Wydawnictwo Naukowe AKAPIT, Krakow 2003. An example of the process is die forging described in specialist literature by P. Skubisz "Technologies of die forging", ARBOR FP, Krakow 2010 and L. Gebrehiwet, Y. Negussie, A. Tadesse " Business Opportunity of Wheel Rim Manufacturing in Ethiopia", International Journal of Advances in Engineering and Management, 2022, vol. 4, pp. 1148-1159. The drop forging process of a magnesium alloy wheel forgings is carried out in three stages - swelling, pre-forging, final forging of a semi-finished product in the form of a roller produced by extrusion. Expensive tool-mounted heating systems are used for the process. This method produces a large technological waste, which is 50% of the forging weight.

[0009] A method of forging a semi-finished product on a hydraulic press is known from the patent PL 237782 Bl, in particular for the production of an aviation fastening, wherein the upper and lower tools having working impressions in the central part are mounted on a hydraulic press with a pressure of 3000 kN and are heated using gas burners to a temperature of 300 ° C . After that , the feed material in the form of a shaped forging cast in sand forms from less malleable magnesium alloys of the magnesium- aluminium-zinc group is heated in a furnace in the temperature range of 400 - 430 ° C , preferably 420 ° C , for up to 45 minutes . The heated input material is then placed in the working impression of the lower tool . After which, the hydraulic press is pressed on the upper tool having two identical blind guide holes with two identical guide pins located on the lower tool and the upper tool is set in progressive downward movement with a velocity of up to 15 mm / s towards the lower tool and the input material is compacted with the working impression of the upper tool and the working impression of the lower tool and a semi-finished product is formed with a lower degree of forging .

[0010] The obj ect of the invention is to produce a forging of the AZ31 magnesium alloy wheel for light vehicles in a single treatment by die forging on a hydraulic press in the form of a preform in metal moulds of the AZ31 magnesium alloy, limiting the labour intensity and energy intensity of the process , the material loss of the products produced by multi-stage forging and machining , and the poor quality of the products produced by machining and casting in sand moulds .

[0011] The essence of the invention is a method of manufacturing a magnesium alloy wheel forging AZ31 for light vehicles on a hydraulic press , characterized in that the upper die having a working impression in the middle part and the lower die having a working impression in the form of a body whose outline is similar to a wheel with circular recesses in the middle is heated in a furnace , then the upper die and the lower die are mounted in the working space of the hydraulic press , after which the preform in the form of a forging cast into metal forms is heated in the furnace , arranged in the working impression of the lower die , after which, as a result of press pressure, the upper die is set in progressive motion towards the lower die, the preform is deformed with the working impression of the upper die and the working impression of the lower die and the wheel forging is formed. The upper die and the lower die, are heated in the furnace to a temperature of 260°C to 300°C, and the preform in the form of a pre-form cast into metal moulds of magnesium alloy AZ31 (Mg- 3Al-lZn) is heated in the furnace at a temperature of 350°C to 400°C for a period of 40 minutes to 45 minutes, whereby the heated forging is deformed with the upper die, driven in a progressive motion towards the lower die with a velocity of 20 mm / s to 40 mm / s with a forging force in the range of 1600.2 kN to 2241.90 kN and a circle forging is formed with a deformation in the range of 6.43 to 12.9. The preform, with a volume of 81315.2 mm3 and a weight of 0.1447 kg, is shaped like a barrel 48.5 mm high and 49.7 mm in diameter at its widest point, so that the lower base is 43.1 mm in diameter and the upper base 42.61 mm in diameter, with a circular cavity 16.93 mm in diameter in the middle of the lower base and 6.5 mm high, while the walls of the barrel are inclined at an angle of 7°.

[0012] Preferably, the preform is heated in a furnace at a temperature of 400°C.

[0013] Preferably, the preform is heated in a furnace for 40 minutes .

[0014] The essence of the invention is also the forging of the wheel generated by the method as set out above.

[0015] It is an advantage of the present invention that the generation of a preform for the forming process allows material savings in relation to the currently used machining technologies and multi-stage forging. The use of a preform for the shaping process makes it possible to obtain more accurate shapes of wheel forgings without excessive spout, which has a positive effect on the reduction of technological waste in relation to the production methods used so far. Another advantage of the present invention is also that the generating method according to the invention allows for the generation of wheel forgings that are characterized by better quality associated with the fragmentation of the structure and obtaining a high surface smoothness , which translates into better mechanical properties in relation to products made by casting in sand moulds and machining .

[0016] The invention is described in the embodiments and in the drawing in which :

[0017] FIG . 1 is a perspective view of a die with a broken-out section with a preform;

[0018] FIG . 2 shows a perspective view of dies in contact with a broken- out section with a wheel forging ;

[0019] FIG . 3 shows a perspective view of the upper die ;

[0020] FIG . 4 shows a perspective view of the lower die ;

[0021] FIG . 5 shows a top perspective view of the upper preform;

[0022] FIG . 6 shows a bottom perspective view of the lower preform;

[0023] FIG . 7 shows a longitudinal section of the preform;

[0024] FIG . 8 shows a top perspective view of a wheel forging;

[0025] FIG . 9 shows a bottom perspective view of a wheel forging ;

[0026] FIG . 10a shows the distribution of deformations in the wheel forging in a top view for the die temperature of 260 ° C and a preform of 350 ° C according to the invention obtained from FEM simulations ;

[0027] FIG . 10b shows the distribution of deformations in the wheel forging in a bottom view for the temperature of dies of 260 ° C and a preform of 350 ° C according to the invention obtained from FEM simulations ;

[0028] FIG . 10c shows the distribution of deformations in the wheel forging in a top view for the temperature of dies of 260 ° C and preform of 400 ° C according to the invention obtained from FEM simulations ; FIG. lOd shows the deformation distribution in the wheel forging in bottom view for a die temperature of 260 °C and a preform of 400°C according to the invention obtained from FEM simulations;

[0029] FIG. lOe shows the distribution of deformations in the wheel forging in a top view for the temperature of dies of 260 °C and preform of 400°C according to the invention obtained from FEM simulations ;

[0030] FIG. lOf shows the distribution of deformations in the wheel forging in a bottom view for the temperature of dies of 260 °C and a preform of 350°C according to the invention obtained from FEM simulations ;

[0031] FIG. 10g shows the deformation distribution in the wheel forging in top view for a die temperature of 300°C and a preform of 400°C according to the invention obtained from FEM simulations;

[0032] FIG. lOh shows the distribution of deformations in the wheel forging in a bottom view for the temperature of dies of 260 °C and a preform of 350°C according to the invention obtained from FEM simulations ;

[0033] FIG. lOi shows the distribution of deformations in the impression in a top view made on the basis of patent document PL237782B1 and obtained from a FEM simulation;

[0034] FIG. 10 j shows the distribution of deformations in the impression in a bottom view made on the basis of patent document PL237782B1 and obtained from FEM simulation;

[0035] FIG. Ila shows a graph of flow curves of AZ31 magnesium alloy cast in metal moulds at 350°C;

[0036] FIG. 11b shows a graph of flow curves of AZ31 magnesium alloy cast in metal moulds at 400 °C;

[0037] FIG. 11c shows a graph of flow curves of AZ31 magnesium alloy cast in metal moulds at 450°C;

[0038] FIG. lid shows a graph of flow curves of AZ61 magnesium alloy cast in sand moulds at 350°C; FIG. lie shows a graph of flow curves of AZ61 magnesium alloy cast in sand moulds at 400°C;

[0039] FIG. Ilf shows a graph of flow curves of AZ61 magnesium alloy cast in sand moulds at 450°C;

[0040] FIG. 12a shows a graph of the dependence of the forging force of the upper die as a function of time for a die temperature of 260°C and a preform of 350°C according to the invention, obtained from FEM simulations;

[0041] FIG. 12b shows a graph of the dependence of the forging force of the upper die as a function of time for a die temperature of 260°C and a preform of 400°C according to the invention, obtained from FEM simulations;

[0042] FIG. 12b shows a graph of the dependence of the forging force of the upper die as a function of time for a die temperature of 260°C and a preform of 400°C according to the invention, obtained from FEM simulations;

[0043] FIG. 12d shows a graph of the dependence of the forging force of the upper die as a function of time for a die temperature of 300°C and an ascending die temperature of 400°C according to the invention obtained from FEM simulations;

[0044] FIG. 12e shows a graph of the dependence of the forging force of the upper die as a function of time, based on patent document PL237782B1 and obtained from FEM simulations.

[0045] For forging an AZ31 magnesium alloy wheel for light vehicles on a hydraulic press, examples 1 - 4 use a preform with a volume of 81315.2 mm3 and a mass of 0.1447 kg, which is barrel-shaped with a height of 48.5 mm and a diameter of 49.7 mm at its widest point, having a lower base 43.1 mm in diameter and an upper base 42.61 mm in diameter, the lower base having a circular recess 16.93 mm in diameter and 6.5 mm high in the middle, and the walls of the barrel being inclined at an angle of 7°. Example 1.

[0046] Method of manufacturing on a hydraulic press a forging of an AZ31 magnesium alloy wheel for light vehicles, intended for a wheelchair .

[0047] The upper die 1 and the lower die 3 having in the middle part working impression la and 3a in the form of a lump, the outline of which is similar to a circle with circular recesses in the middle, were heated in a furnace at a temperature of 260°C and mounted in the working space of a hydraulic press. Subsequently, the forging preform 2a in the form of a preform cast into magnesium alloy metal moulds AZ31 (Mg-3Al-lZn) according to ASTM B107-13 was heated in a furnace at 350°C for 45 minutes. The preform according to the invention is shaped like a barrel with a volume of 81315.2 mm3 and a weight of 0.1447 kg, a height of 48.5 mm and a diameter of 49.7 mm at its widest point, a lower base with a diameter of 43.1 mm and a upper base with a diameter of 42.61 mm, with the lower base also having a circular recess in the middle part with a diameter of 16.93 mm and a height of 6.5 mm, while the walls of the barrel are inclined at an angle of 7° .

[0048] The forging preform 2a was then arranged in the working impression 3a of the lower die 3. Then, as a result of the pressure of the press, the upper die 1 was set in a progressive motion with a velocity of 20 mm / s to 40 mm / s towards the lower die 3 and the forging preform 2a was deformed with the working impression la of the upper die 1 and the working impression 3a of the lower die 3 with a maximum forging force of 2241.9 kN and the forging of the wheel 2b was shaped with a maximum deformation 11.

[0049] Example 2.

[0050] The method of producing a forging of a magnesium alloy wheel AZ31 for light vehicles on a hydraulic press, intended for a wheelchair, according to Example 1, wherein the forging preform 2a was heated in a furnace at a temperature of 400°C for 40 minutes . The forging preform 2a was then arranged in the working impression 3a of the lower die 3. Then, as a result of the pressure of the press , the upper die 1 was set in a progressive motion with a velocity of 20 mm / s to 40 mm / s towards the lower die 3 and the forging preform 2a was deformed with the working impression la of the upper die 1 and the working impression 3a of the lower die 3 with a maximum forging force of 1600 . 2 kN and the forging of the wheel 2b was shaped with a maximum deformation of 10 . 7 .

[0051] Example 3 .

[0052] The method of producing a forging of a magnesium alloy wheel AZ31 for light vehicles on a hydraulic press , intended for a wheelchair according to Example 1 , wherein the upper die 1 and the lower die 3 were heated in a furnace at a temperature of 300 ° C , the forging preform 2a was heated in a furnace at a temperature of 350 ° C for 45 minutes . The forging preform 2a was then arranged in the working impression 3a of the lower die 3 . Then, as a result of the pressure of the press , the upper die 1 was set in a progressive motion with a velocity of 20 mm / s to 40 mm / s towards the lower die 3 and the forging preform 2a was deformed with the working impression la of the upper die 1 and the working impression 3a of the lower die 3 with a maximum forging force of 2284 . 1 kN and the forging of the wheel 2b was shaped with a maximum deformation of 12 . 9 .

[0053] Example 4 .

[0054] The method of producing a forging of a magnesium alloy wheel AZ31 for light vehicles on a hydraulic press , intended for a wheelchair according to Example 1 , wherein the upper die 1 and the lower die 3 were heated in a furnace at a temperature of 300 ° C , the forging preform 2a was heated in a furnace at a temperature of 400 ° C for 40 minutes . The forging preform 2a was then arranged in the working impression 3a of the lower die 3 . Then, as a result of the pressure of the press , the upper die 1 was set in a progressive motion with a velocity of 20 mm / s to 40 mm / s towards the lower die 3 and the forging preform 2a was deformed with the working impression la of the upper die 1 and the working impression 3a of the lower die 3 with a maximum forging force of 1861 . 7 kN and the forging of the wheel 2b was shaped with a maximum deformation of 6 . 43 .

[0055] A wheel forgings made of AZ31 magnesium alloy with higher mechanical properties resulting from a more favorable structure of the shaped product in relation to the products made by casting and machining were obtained .

[0056] A comparative analysis was carried out using the Finished Element Method ( FEM) of a method of manufacturing on a hydraulic press a forging of an AZ31 magnesium alloy wheel for light vehicles according to the invention - model 1 (Ml . 1 - Ml . 4 ) and a method of forging a semi-finished product on a hydraulic press , especially for the manufacture of an aircraft mount based on patent document PL237782B1 - model 2 (M2 ) . The numerical analysis was carried out in a system designed to simulate plastic working processes - 3D Deform in accordance with the parameters adopted in Table 1 . For the FEM analysis , the developed models of magnesium alloy materials AZ31 were used and AZ 61 magnesium alloy based on plastometric tests .

[0057] Table 1 - Comparison of the method according to the invention with the state of the art

[0058] These tests were carried out for a metal-cast magnesium alloy of grade AZ31 according to ASTM B107 -13 and a sand-cast magnesium alloy of grade AZ 61 according to ASTM B951-10 with the chemical composition presented in Table 2 . Table 2 - The chemical composition of the magnesium alloy AZ31 used in the process according to the present invention according to ASTM B107-13 and the magnesium alloy AZ61 according to ASTM B951-10 used in the process according to PL 237782 Bl

[0059] Plastometric tests were performed on a deformation dilatometer at temperatures of 350°C, 400°C, 450°C at deformation speeds of 0.1 s-1; 1 s-1; 10 s-1. Based on the obtained results from the measurements, the flow curves for the AZ31 alloy presented in the graphs of Fig. Ila - 11c and for magnesium alloy AZ61 shown in the graphs of FIGS, lid - Ilf. In the numerical simulations, the following were analysed: the maximum shaping force of the upper die / upper tool as a function of time, the maximum deformation in the shaped products, the contact area of the shaped forging with the upper die / upper tool, the contact area of the shaped forging with the lower die / lower tool for both methods analysed .

[0060] The maximum forging force obtained from the numerical analysis and the maximum deformation in the shaped forging according to the invention - Ml are shown in FIG.12a - 12d and FIG. 10a - lOh. The maximum forging force and maximum deformation in the shaped impression obtained from the numerical analysis performed on the basis of patent document PL 237782 Bl - M2 are presented in the graph of FIG. 12e and Fig. lOi and lOj . List of reference symbols

[0061] 1 - upper die la - working impression of the upper die

[0062] 2a - forging preform

[0063] 2b - wheel forging

[0064] 3 - lower die

[0065] 3a - working impression of the lower die Vi - upper die velocity

Claims

Claims1. Method of manufacturing, on a hydraulic press, an AZ31 magnesium alloy wheel forging for light vehicles, characterised in that the upper die (1) with a working impression (la) in the centre and a lower die (3) with a working impression (3a) in the form of a lump whose outline resembles a circle with circular recesses in the centre, is heated in a furnace to a temperature of 260 °C to 300 °C, after which the heated upper die (1) and lower die (3) are mounted in the working space of a hydraulic press with a pressure of 1600 kN to 2242 kN, and then the forging (2a) in the form of a preform cast into metal moulds of magnesium alloy AZ31 (Mg-3Al-lZn) is heated in a furnace to a temperature between 350 °C and 400 °C for 40 to 45 minutes, then the heated preform (2a) is placed in the working impression (3a) of the lower die (3) , then the hydraulic press is applied to the upper die (1) , setting the upper die (1) in a downward progressive motion at a speed (VI) from 20 mm / s to 40 mm / s in the direction of the lower die (3) and compacting the preform (2a) with the working impression (la) of the upper die (1) and the working impression (3a) of the lower die (3) , shaping the forging (2b) of the wheel with a deformation ranging from 6.43 to 12.9.

2. The method according to claim 1, characterised in that the preform (2a) is barrel-shaped, with a volume of 81315.2 mm3 , a weight of 0.1447 kg, a height of 48.5 mm and a diameter of 49.7 mm at its widest point, the base is 43.1 mm in diameter and the upper base 42.61 mm in diameter, with a circular recessof 16.93 mm in diameter and 6.5 mm high in the middle of the base, and the walls of the barrel inclined at an angle of 7°.

3. The method according to claim 1, characterised in that the forging preform (2a) is heated to 400 °C, in 40 min.

4. The wheel forging is generated as defined in claims 1 to 3.

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