Drop forging method of magnesium wheel forgings from a preform cast into metal moulds and a magnesium wheel forging shaped in this way

Abstract

The subject of the invention is a method of drop forging on a hammer of a magnesium wheel forgings from a die casting for metal forms and a magnesium wheel forgings shaped in this way, characterized in that the upper drop forging tool (1) having a finishing impression (1a) in the middle part and the lower drop forging tool (3) having a finishing impression (3a) in the central part, and the finishing impression (1a) and (3a) are in the form of a solid whose outline is similar to a wheel with circular valleys in the middle, is heated in a furnace to a temperature from 260 °C to 300 °C, after which the heated upper drop forging tool (1) is mounted to the forging hammer with a dovetail (1b), and the heated lower drop forging tool (3) is mounted to the die hammer with a dovetail (3b), and then the blank (2a) cast to the metal AZ91 (Mg-9AlZn-1) allocks are heated at a temperature from 350 °C to 400 °C, in the period from 30 minutes to 35 minutes, after which the heated blank (2a) cast into metal moulds is placed and centered in the finishing impression (3a) of the lower drop forging tool (3), then the upper drop forging tool (1) is set in a progressive movement down with a velocity (V1) of 6 m / s towards the lower drop forging tool (3) and the impact of the upper drop forging tool (1) with a maximum impact energy in the range of 6.11 to 7.51 kJ, the forging preform (2a) cast into metal moulds is compacted with the finishing impression (1a) of the upper drop forging tool (1) and the finishing impression (3a) of the lower drop forging tool (3), shaping the forging of the wheel (2b) with a deformation in the range from 4.42 to 11.1. The subject matter of the invention is also a wheel forging produced by the method set forth above.

Description

[0001] DROP FORGING METHOD OF MAGNESIUM WHEEL FORGINGS FROM A PREFORM CAST INTO METAL MOULDS AND A MAGNESIUM WHEEL FORGING SHAPED IN THIS WAY

[0002] The subj ect-matter of the invention is a method of forging a magnesium wheel forging from a forging cast into metal moulds on a die hammer and a magnesium wheel forging shaped in this way .

[0003] So far , methods of shaping magnesium alloy wheels such as casting , machining, die forging are known and used .

[0004] For the shaping 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. . 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 shaping 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 semi-finished product 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. A method of forging a semi-finished product on a hammer is known from the description of the patent PL 237778 Bl , in particular for the production of an aviation fastening , wherein the upper and lower dies having working impressions in the central part are heated in a furnace using gas burners to a temperature of 300 ° C and placed on a forging hammer with an impact energy of 36 kJ and a hammer mass of 1000 kg . The input material in the shape of a shaped forging preform cast in sand moulds 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 placed in the working impression of the lower die . Subsequently, the upper die is set in progressive motion with a velocity of up to 8 m / s towards the lower die and the input material is compacted with the working impression of the upper die and the working impression of the lower die and a semi-finished product is formed with a lower degree of forging . Numerical and experimental studies for the method according to the patent PL 237778 Bl is shown on the example of magnesium alloy AZ 61 in the article by A . Dziubinska, P . Surdacki , K . Maj ers ki "The Analysis of Deformability, Structure and Properties of AZ 61 Cast Magnesium Alloy in a New Hammer Forging Process for Aircraft Mounts" , Materials , 2021 , vol . 14 , no . 10 , pp . 1-25 . It has been proven to improve the functional and mechanical properties of castings subj ected to heat-plastic processing according to the method from the patent description .

[0009] The obj ect of the invention is to shape the forging of the AZ 91 magnesium alloy wheel in a single forging operation in a finishing impression on a die hammer of the AZ 91 magnesium alloy die casting die in metal moulds , reducing the material intensity, labor intensity, and energy intensity of the process .

[0010] The essence of the invention is a method of forging a magnesium wheel forgings on a forging hammer ram from a forging preform cast for metal forms, characterized in that the upper drop forging tool and the lower drop forging tool having finishing impressions in the form of a body whose outline is similar to a wheel with circular recesses in the middle are heated in a furnace, and then the upper drop forging tool with a dovetail is mounted to the forging hammer ram and the lower drop forging tool is mounted with a dovetail tail to the forging hammer ram, after which the forging cast for metal forms is heated in the furnace, placed and centered in the finishing impression of the lower drop forging tool, after which the upper drop forging tool is set in a progressive movement towards the lower drop forging tool and the impact of the upper drop forging tool is crushed the forging cast into metal forms with the finishing impression of the upper drop forging tool and the finishing impression of the lower drop forging tool and the wheel is formed. The upper drop forging tool and the lower drop forging tool are heated in a furnace to a temperature between 260°C and 300°C, and the forging cast into AZ91 (Mg-9A1- IZn) magnesium alloy metal moulds are heated in a furnace at a temperature between 350°C and 400°C for a time between 30 minutes and 35 minutes, and the heated forging cast into metal moulds is crushed with an upper drop forging tool set in a progressive motion towards the lower drop forging tool with a velocity of 6 m / s with a maximum impact energy in the range from 6.11 to 7.51 kJ and a wheel forging is formed with a maximum deformation in the range from 4.42 to 11.1. The forging preform cast for metal moulds with a volume of 81961.7 mm3 and a weight of 0.1569 kg has the shape of a barrel with a height of 25.31 mm and a diameter of 65.9 mm at its widest point, which has a lower base with a diameter of 62.97 mm and an upper base with a diameter of 63.29 mm, where in the lower base there is a circular recess with a diameter of 18.22 mm and a height of 6.8 mm, and the walls of the barrel are inclined at an angle of 4°. Preferably, the forging cast into the metal forms is heated in a furnace at a temperature of 400 ° C , preferably within 30 minutes .

[0011] The essence of the invention is also the forging of the wheel shaped by the method as set out above .

[0012] It is an advantage of the present invention that the use of a cast blank for the forming process allows material savings in relation to the currently used machining technologies and multi-stage forging . The use of a cast forging for the shaping process makes it possible to obtain more accurate shapes of wheel forgings without excessive flash, which has a positive effect on the reduction of technological waste in relation to the production methods used so far .

[0013] Another advantage of the present invention is also that the shaping method according to the invention allows for the production 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 .

[0014] The invention is described in the embodiments and in the drawing in which :

[0015] FIG . 1 shows a perspective view of forging tools with a tear-off with a preform cast into metal moulds ;

[0016] FIG . 2 shows a perspective view of forging tools in contact with a wheel forging ;

[0017] FIG . 3 illustrates a perspective view of an upper drop forging tool ;

[0018] FIG . 4 shows a perspective view of the lower drop forging tool ;

[0019] FIG . 5 shows a perspective view from above of a preform cast into metal moulds ; FIG. 6 shows a bottom perspective view of a preform cast into metal moulds;

[0020] FIG. 7 shows a longitudinal section of a preform cast into metal moulds ;

[0021] FIG. 8 shows a top perspective view of a wheel forging;

[0022] FIG. 9 shows a bottom perspective view of a wheel forging;

[0023] FIG. 10a shows the distribution of deformations in the wheel forging in a top view for the temperature of forging tools 260°C and the forging cast into metal moulds 350 °C according to the invention obtained from FEM simulation;

[0024] FIG. 10b shows the distribution of deformations in the wheel forging in a bottom view for the temperature of forging tools 260°C and the forging cast into metal moulds 350°C according to the invention obtained from the FEM simulation;

[0025] FIG. 10c shows the distribution of deformations in the wheel forging in a top view for the temperature of forging tools 260°C and the forging cast into metal moulds 400°C according to the invention obtained from FEM simulation;

[0026] FIG. lOd shows the distribution of deformations in the wheel forging in the bottom view for the temperature of forging tools 260°C and the forging cast into metal moulds 400°C according to the invention obtained from the FEM simulation;

[0027] FIG. lOe shows the distribution of deformations in the wheel forging in a top view for the temperature of forging tools 300°C and the forging cast into metal moulds 350 °C according to the invention obtained from FEM simulation;

[0028] FIG. lOf shows the distribution of deformations in the wheel forging in a bottom view for the temperature of forging tools 300°C and the forging cast into metal moulds 350°C according to the invention obtained from the FEM simulation; FIG. 10g shows the deformation distribution in the wheel forging in top view for the temperature of forging tools 300 °C and the forging cast into metal moulds 400°C according to the invention obtained from FEM simulation;

[0029] FIG. lOh shows the distribution of deformations in the wheel forging in a bottom view for the temperature of forging tools 300°C and the forging cast into metal forms 400°C according to the invention obtained from the FEM simulation;

[0030] FIG. lOi shows the distribution of deformations in the blank in a top view made on the basis of patent document PL 237778 Bl and obtained from a FEM simulation;

[0031] FIG. lOj shows the distribution of deformations in the blank in a bottom view made on the basis of patent document PL 237778 Bl and obtained from FEM simulation;

[0032] FIG. Ila shows a graph of flow curves of AZ91 magnesium alloy cast in metal moulds at 350°C;

[0033] FIG. 11b shows a graph of flow curves of AZ91 magnesium alloy cast in metal moulds at 400 °C;

[0034] FIG. 11c shows a graph of flow curves of AZ91 magnesium alloy cast in metal moulds at 450°C;

[0035] FIG. lid shows a graph of flow curves of AZ61 magnesium alloy cast in sand moulds at 350°C;

[0036] FIG. lie shows a graph of flow curves of AZ61 magnesium alloy cast in sand moulds at 400°C;

[0037] FIG. Ilf shows a graph of flow curves of AZ61 magnesium alloy cast in sand moulds at 450°C;

[0038] FIG. 12a shows a graph of the impact energy of the upper tool as a function of time for the temperature of the forging tools 260°C and the forging preform cast into metal moulds 350°C according to the invention, obtained from the FEM simulation; FIG . 12b shows a graph of the impact energy of the upper tool as a function of time for the temperature of the forging tools 260 ° C and the forging preform cast into metal moulds 400 ° C according to the invention, obtained from the FEM simulation;

[0039] FIG . 12 c shows a graph of the impact energy of the upper tool as a function of time for the temperature of the forging tools 300 ° C and the forging cast into metal moulds 350 ° C according to the invention, obtained from the FEM simulation;

[0040] FIG . 12d shows a graph of the impact energy of the upper tool as a function of time for a temperature of forging tools 300 ° C and a forging preform cast into metal moulds 400 ° C according to the invention obtained from a FEM simulation;

[0041] FIG . 12e shows a graph of the impact energy of the upper drop forging tool as a function of time based on patent document PL 237778 Bl and obtained from a FEM simulation .

[0042] Forging on a die hammer of a forging of a magnesium wheel made of a forging cast into metal forms and a forging of a magnesium wheel shaped in this way was used in Examples 1 - 4 a forging cast into metal forms with a volume of 81961 . 7 mm3 and a weight of 0 . 1569 kg, which has the shape of a barrel with a height of 25 . 31 mm and a diameter of 65 . 9 mm at its widest point , having a lower base with a diameter of 62 . 97 mm and an upper base with a diameter of 63 . 29 mm, where in the lower base there is a circular recess with a diameter of 18 . 22 mm and a height of 6 . 8 mm, and the walls of the barrel are inclined at an angle of 4° .

[0043] Example 1 .

[0044] Forging method on the die hammer of the magnesium wheel forgings into metal moulds and a forging of a magnesium wheel shaped in this way, intended for a wheelchair . The upper drop forging tool 1 and the lower drop forging tool 3 having in the middle part finishing impressions la and 3a in the form of a solid, the outline of which is similar to a circle with circular valleys in the middle , were heated in a furnace at a temperature of 260 ° C . Then the upper drop forging tool 1 with a dovetail lb was mounted to the die hammer hammer and the lower drop forging tool 3 was mounted with a dovetail 3b to the die hammer sabotage . Then the forging 2a cast into magnesium alloy metal moulds AZ 91 (Mg- 9A1- IZn ) according to ASTM B107 -13 was heated in a furnace at 350 ° C for 35 minutes . Then, the forging preform 2a cast into metal moulds was placed and centered in the finishing impression 3a of the lower drop forging tool . Then, the upper drop forging tool 1 was set in a progressive motion with a velocity of 6 m / s towards the lower drop forging tool 3 and the impact of the upper drop forging tool 1 was crushed the forging 2a cast into metal moulds with a finishing impression la of the upper drop forging tool 1 and a finishing impression 3a of the lower drop forging tool 3 with a maximum impact energy of 7 . 45 kJ and a wheel forging 2b was shaped with a maximum deformation of 4 . 42 .

[0045] Example 2 .

[0046] Forging method on a die hammer of the magnesium wheel forgings from a forging cast into metal moulds and a magnesium wheel forging shaped in this way , intended for a wheelchair according to Example 1 , wherein the forging 2a cast into metal moulds was heated in a furnace at a temperature of 400 ° C for 30 minutes . Then, the ferrule 2a cast into metal moulds was placed and centered in the finishing impression 3a of the lower drop forging tool . Then the upper drop forging tool 1 was set in a progressive motion with a velocity of 6 m / s towards the lower drop forging tool 3 and the impact of the upper drop forging tool 1 was crushed a blank 2a cast into metal moulds with a finishing impression la of the upper drop forging tool 1 and a finishing impression 3a of the lower drop forging tool 3 with a maximum impact energy of 6 . 11 kJ and a wheel forging 2b was formed with a maximum deformation of

[0047] 8 . 88 .

[0048] Example 3 .

[0049] Forging method on a die hammer of the magnesium wheel forgings of a die-casting forging for metal moulds and a magnesium wheel forging shaped in this way for a wheelchair according to Example 1 , wherein the upper drop forging tool 1 and the lower drop forging tool 3 were heated in a furnace at a temperature of 300 ° C , the die-casting forging 2a forged for metal moulds was heated in a furnace at a temperature of 350 ° C for 35 minutes . Then, the ferrule 2a cast into metal moulds was placed and centered in the finishing impression 3a of the lower drop forging tool . Then, the upper drop forging tool 1 was set in a progressive motion with a velocity of 6 m / s towards the lower drop forging tool 3 and the impact of the upper drop forging tool 1 was crushed the forging 2a cast into metal moulds with a finishing impression la of the upper drop forging tool 1 and a finishing impression 3a of the lower drop forging tool 3 with a maximum impact energy of 7 . 51 kJ and a wheel forging 2b was shaped with a maximum deformation of 11 . 1 .

[0050] Example 4 .

[0051] Forging method on the die hammer of the magnesium wheel forgings from a forging cast into metal moulds and a forging of a magnesium wheel shaped in this way, intended for a wheelchair , implemented according to Example 1 , wherein the upper drop forging tool 1 and the lower drop forging tool 3 were heated in a furnace at a temperature of 300 ° C, the forging 2a cast into metal forms was heated in a furnace at a temperature of 400 ° C for 30 minutes . Then, the ferrule 2a cast into metal moulds was placed and centered in the finishing impression 3a of the lower drop forging tool . Then, the upper drop forging tool 1 was set in a progressive motion with a velocity of 6 m / s towards the lower drop forging tool 3 and the impact of the upper drop forging tool 1 was crushed a forging preform 2a cast into metal moulds with a finishing impression la of the upper drop forging tool 1 and a finishing impression 3a of the lower drop forging tool 3 with a maximum impact energy of 6 . 13 kJ and a wheel forging 2b with a maximum deformation of 4 . 39 was formed .

[0052] A wheel forging made of AZ 91 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 .

[0053] A comparative analysis was carried out using the Finished Element Method ( FEM) of forging the magnesium wheel forgings on the die hammer from a forging cast into metal forms and a forging of a magnesium wheel shaped in this way according to the invention - model 1 (Ml . 1 - Ml . 4 ) and the method of forging a semi-finished product on a hammer , especially for the production of an air fastening based on the patent document PL 237778 Bl - 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 AZ 91 were used and AZ 61 magnesium alloy based on plastometric tests .

[0054] Table 1 - Comparison of the method according to the invention with the state of the art

[0055]

[0056]

[0057] These tests were carried out for a metal-cast magnesium alloy of grade AZ91 according to ASTM B107-13 and a sand-cast magnesium alloy of grade AZ61 according to ASTM B951-10 with the chemical composition presented in Table 2.

[0058] Table 2 - The chemical composition of the magnesium alloy AZ91 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 237778 Bl.

[0059] Plastometric tests were performed on a deformation dilatometer at temperatures of 350°C, 400°C, 450°C with a deformation velocities of 0.1 s-1; 1 s-1; 10 s-1. Based on the obtained results from the measurements, the flow curves for the AZ91 alloy presented in the graphs of FIG. Ila - 11c and for magnesium alloy AZ61 shown in the graphs of FIGS. lid - Ilf. In numerical simulations, the following were analyzed: the maximum impact energy of the upper tool as a function of time , the maximum deformation in the shaped products , the contact area of the shaped forging with the upper tool , the contact area of the shaped forging with the lower tool for both analyzed methods . The maximum impact energy obtained from the numerical analysis and the maximum deformation in the shaped forging according to the invention - Ml . 1 - Ml . 4 is shown in FIG . 12a - 12d and FIG . 10a - l Oh . The maximum impact energy and maximum deformation in the shaped blank obtained from the numerical analysis performed on the basis of patent document PL 237778 Bl - M2 are presented in the graph of FIG . 12e and FIG . lOi and 10 j .

[0060] List of reference symbols

[0061] 1 - upper drop forging tool la - finishing impression of the upper drop forging tool lb - dovetail of the upper drop forging tool

[0062] 2a - forging preform cast into metal moulds

[0063] 2b - wheel forging

[0064] 3 - lower drop forging tool

[0065] 3a - finishing impression of the lower drop forging tool 3b - dovetail of the lower drop forging tool

[0066] Vi - upper drop forging tool speed

Claims

Claims1. Method of drop forging on the hammer of the magnesium wheel forgings from a preform cast into metal moulds characterized in that the upper drop forging tool (1) having a finishing impression in the middle part (la) and a lower drop forging tool (3) having a finishing impression (3a) in the middle part, and the finishing impressions (la) and (3a) are in the form of a lump whose outline is similar to a circle with circular recesses in the center, is heated in a furnace to a temperature of 260 °C to 300 °C, after which the heated upper drop forging tool (1) is mounted to the die hammer ram by means of a dovetail (lb) , and the heated lower drop forging tool (3) is mounted to the die hammer anvil block by means of a dovetail (3b) , and then the forging preform cast (2a) into magnesium alloy metal moulds AZ91 (Mg-9Al-lZn) is heated in a furnace to a temperature between 350 °C and 400 °C for a time between 30 minutes and 35 minutes, after which the heated forging preform cast (2a) into the metal moulds is placed and centered in the finishing impression (3a) of the lower drop forging tool (3) , then the upper drop forging tool (1) is set in a downward progressive motion with a velocity of (VI) 6 m / s towards the lower drop forging tool (3) and the upper drop forging tool (1) is struck with a maximum impact energy in the range from 6.11 to 7.51 kJ, the forging cast (2a) into metal moulds is compacted with the finishing impression (la) of the upper drop forging tool (1) and finishing impression (3a) of the lower drop forging tool (3) ,shaping the wheel forgings (2b) with deformation in the range from 4.42 to 11.1.

2. The method according to claim 1, characterized in that the forging preform cast (2a) for metal forms has the shape of a barrel with a volume of 81961.7 mm3, a weight of 0.1569 kg, a height of 25.31 mm and a diameter 65.9 mm at its widest point, the lower base has a diameter of 62.97 mm and the upper base has a diameter of 63.29 mm, wherein in the lower base there is also a circular recess with a diameter of 18.22 mm and a height of 6.8 mm, and the walls of the barrel are inclined at an angle of 4°.

3. The method according to claim 1, characterized in that the forging cast (2a) into metal moulds is heated to 400 °C for 30 minutes .

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

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