Engine connecting rod ruptures analyse divides new technology

Brittleness ruptures the theoretical foundation of this craft is to rupture mechanical medium brittleness ruptures academic. According to rupturing mechanical and knowable, rupture surface of the crackle in the process has form of 3 kinds of displacement normally, stretch namely model, around slippage, plane cuts cut type. Suffer when the object perpendicular at rupturing planar when stress is tensile, belong to stretch model rupture, this is brittleness ruptures the form of generation and condition. Brittleness ruptures have the following hair to give birth to a characteristic: Stress of job of the susceptive when 1) ruptures is inferior, normally far under material succumb intensity, plasticity is out of shape small; 2) ruptures suffer temperature the impact is bigger; Direction of 3) fracture surface and stress photograph is perpendicular. Connecting rod judges analyse technology is afore-mentioned characteristics that according to brittleness ruptures, give V slot through leaving in connecting rod is big inside, bring to bear on next perpendicular rupture at booking of the face stress, satisfy the hair that brittleness ruptures to lay a condition, make one lid is in gonnecting rod body not to produce plasticity metabolic circumstance to fall to be departed. Should pay close attention to the following problems: Material of 1) semifinished product; 2)V chamfer appearance and place want stress relationship; 3) operates temperature. 2.

Semifinished product material produces brittleness more easily to rupture as a result of brittleness material, comfortable the connecting rod that makes at using analyse technology, basically use undermentioned the semifinished product of 3 kinds of material: 1) powder forgings semifinished product; 2) malleable iron; 3)70 high-carbon steel. The semifinished product with these 3 kinds of simple material, brittleness can come true to rupture below room temperature, connecting rod is big aperture does not produce apparent plasticity to be out of shape, its deflection 40 μ of ≤ M, after classics machine is machined, its circularity error can be decreased for 3 μ M. In addition, semifinished product of 55 forged steel also can use 45 ～ analyse technology undertakes connecting rod is made, but must assure to be in - when 40 ℃ , caikeshi shows brittleness to rupture, assure to bilge after cracking be out of shape enough small. 3.

Temperature influence ruptures section plane as punch face same, normally cent is 3 areas, by rupture the source is outward and ordinal can divide for fiber area, radiative area, cut a lip (2) seeing a picture. When the radiative area when section is wider, the plasticity that represents material is poor, brittleness is bigger. Conversely, fiber area is larger, the plasticity that makes clear material and tenacity are better. How to increase radiative area breadth, width of contractible fiber area, it is the condition that implementation brittleness ruptures. Graph section plane sketch map shows 2 fracture surface 3 times to be opposite for temperature fracture surface 3 element the influence of each area size, material is 40Cr, see from inside the graph, when temperature under room temperature when, radiative area already increased significantly namely, the craft breaking analyse that issues executive connecting rod for room temperature so provided experimental safeguard. The steel of 70 above carbon of mechanical function and 40Cr close, accord with the temperature partition trend that the graph shows 4 times likewise. Graph the influence that 3 temperature rupture to brittleness pursues 4 rupture the relation curve 　 of intensity and crack depth 4.

Groove deepness A and rupture the relation of intensity by the graph 4 visible, crackle (V form chamfer) deepness and rupture intensity σ C becomes inverse ratio, be worth to particular stress namely, existing a critical crack depth Ac, when crack depth is less than this value, crackle is stable, when be worth hereat greatly only, crackle is broken firm, crackle heals deep, the critical fracture stress of material heals low. The concern of deepness A and σ is as follows: When the structure that brings gap gets outside force, in crackle most advanced KIC(of factor of strength of strength of around generation all says material ruptures again tenacity is worth) pilot stress. When outside force increases, the stress intensity factor with most advanced crackle increases subsequently, achieve some when KI when critical value KIC, crackle happening is broken firm, structural brittleness ruptures, namely KI ≥ KIC. To certain material, KIC is one constant value, can check a watch to beg, also can decide through checking a method (more accurate) . KIC cost is lower, produce brittleness more easily to rupture. The test that is worth to KIC consequently is calculated, should be the stress that studies analyse mechanism. According to KIC principle, the gap that gives measure to can be calculated an action stress. Conversely, to giving the component part of action stress, can calculate critical crack size. This one principle ruptures for connecting rod analyse cent provided design basis. 4, the design design of the device that break analyse ruptures reasonably analyse cent device is to carry out rupture the crucial factor that analyse assigns. Its design a principle is: 1) ruptures force can instantaneous is abrupt action, because,this is of force apply acceleration to have main effect to realizing brittleness to rupture. 2) is in this one process, connecting rod wants firm installation cannot activity. In separate course, gonnecting rod body, lid can produce the sharp movement that deviates from only, the opposite roll between any gonnecting rod body, Gai Zhi, can cause needless plasticity be out of shape bring about cannot undertake closing normally installing in the future. The device that break analyse basically includes: Fixed base, connecting rod builds pedestal of pedestal, gonnecting rod body, every pedestal deserves to have guide, can make pedestal is inside certain limits, edge slideway is done perpendicular move planarly at rupturing, still have the axis of the core that divide valve that can insert wedge piece to undertake depart to wait. 5, the last word divides new technology to have follow-up treatment as a result of connecting rod analyse working procedure is little, make this low, gonnecting rod body, lid assemble precision tall, analyse divides carrying capacity advanced advantage, at present this kind of new technology gets be popularizinged quickly in product line of foreign connecting rod. As the development of our country auto industry, the development application of all sorts of advanced production technologies is to raise the car product quality, certain way that reduces cost. Accordingly, answer to increase research to develop strength in this one domain, to this will be popularized anew in our country henceforth craft does good technology to lay in. CNC Milling CNC Machining