New energy air conditioning compressor bearing forming technology research

New energy air conditioning compressor bearing 2019 - forming technology research 04 - Author: 10 Jin Fengzhen Huang Ting new energy vehicles is the direction of future development, as an important parts of automobile air conditioning compressor and the reasonable design of the bearing and economic manufacturing, to ensure that the compressor performance and cost reduction is of great significance. In automobile air conditioning compressor, with a high speed shaft bearing and orbiting scroll to cooperate with each other, under the complex stress state and high stress value, high speed and worked long hours, with its high performance requirements. Traditional gravity casting production efficiency is low, easy to produce the internal defects such as blow hole, shrinkage, as the new energy car sales increased, have apparently can't meet the production requirements. The article adopts the method of cast to generation, with DEFORM - 3 d of new energy automotive air conditioning compressor housings are numerically simulated and analyzed in the process of forming metal flow rule, a pre forging blocking, put forward in this paper. and then back pressure closed die forging forming of forging process, not only can improve the mechanical properties of the bearing, improve material utilization, can greatly improve production efficiency. Parts structure analysis of new energy automobile air conditioning compressor and the 3 d figure of the bearing as shown in figure 1. It can be seen that bearing small surface complex shape, wall thickness, The thinnest place to 4 mm) More features, internal staircase. Metal illiquid its forming process, the forging load spurt, billet prone to cracking, folding and filling difficult problems. One step forming with the method of closed die forging of the original billet forging forming at a time. According to the position relationship and its volume principle, set up two kinds of schemes of billet size: one way for & phi; 80毫米× 18毫米( High ratio of 0. 225). , scheme 2 & phi; 94mm× 13mm（ High ratio 0. 138). 。 The DEFORM - 3 d software set in the finite element pre-treatment files, including blank in order to establish the model of 4032 aluminum alloy on its own, the mold for the rigid body, by using the coulomb friction model, according to the production conditions set the friction factor is 0. 25, billet and the mold temperature is 450 ℃ and 200 ℃ respectively, the descending speed of 5 mm/s. As shown in figure 2 for plan 1 and 2 damage value distribution. As you can see, under the two kinds of schemes of damage value are more than 1, and the outer surface of the concentration distribution in the ladder, this is due to the thin wall, deep inner cavity, and 4032 aluminum alloy and plastic is poorer, liable to occur in a forming cracking, folding, load is too high. Two-step forming step to avoid forming the problem of cracking and high load is put forward in two steps in the process of the forging + finish forging forging process of forming the parts, in order to ensure the metal flow smoothly everywhere at the same time, make the metal in the three-way compressive stress state, reduce the fracture orientation in the process of forming, and reduce the forming load, adopting with back pressure die forming, finite element model is shown in figure 3. First on the cylinder billet forging with the steps of forging blank, reoccupy pre forging blank forming a bearing seat. Parameter setting is consistent with the step of forming, among them, the back pressure applying moving boundary conditions require a separate body, maximum back pressure 20 t, back pressure range of 0. As the module of back pressure downward moves down, also in the blank in contact with the back pressure when the body begins to back pressure, when the back pressure of body in contact with the limit board to stop movement, closed extrusion. Analysis of forming process in the back pressure block type of die forging forming, considering the bearing internal ladder is more, set up, comparing the two kinds of situations as shown in figure 4. At the bottom of the three schemes for slotless stepped blank: base circle & phi; 90mm× 12 mm, convex platform & phi; 48毫米× 13mm； Plan for four at the bottom of the slotted stepped blank: base circle & phi; 91mm× 11. 7 mm, convex platform & phi; 48毫米× 16 mm, the bottom of the groove & phi; 43毫米× 4mm。 From the simulation result can be seen in figure 5, two kinds of package material damage values are less than 1, and effectively improve the cracking problem, and ultimately forming load is less than 90 t, in the current equipment affordable. As shown in figure 6 for bearing forming metal flow velocity field. It can be seen that when the metal flow after a distance ladder when in contact with the punch, began to appear, metal part of the metal will be affected by the effect of lower punch and upward mobility, when the downward movement of the metal flow produce folding defect. Without slot blank during forming, metal flow with large velocity difference, there is cracking tendency. Due to the early forming back pressure force is small, the metal flow resistance is small, so the velocity field is dense and velocity of flow is big, but in the middle and later periods of the forming, because the back pressure effect, metal flow interference, slow part flow fast, eventually make face everywhere converge speed. Die stress analysis diagram 7 respectively two step forming stress of upper die and lower die stress, when the back pressure stress distribution nephogram. You can see that the mould maximum stress within 100 mpa, so choosing H13 steel as mould material is feasible. At the same time, the mold stress larger areas concentrated in the corner and ladder, the first step of upper die and lower die hole edge and the back pressure of external stress at the edge of the premises by the larger, easy cause mould wear forming process, and influence the forming quality of the bearing. Conclusion (1) to two step closed die forging billet size comparison of the simulation, prone to cracking, folding, found a forming load is too large. Adopt the method of two step forging forming, bearing the forming of good quality. In two step forging forming, set up two kinds of forging blank, found in the bottom of the grooved pre forging billet forming metal flow is relatively superior, and finish forging forming process in the back pressure under the action of body, billet in three-way compressive stress state, the plastic, cracking tend to be small. Source: the forging and stamping. 17, 2018