Vertical injection molding machine trapezoidal threaded end of the rod to optimize unloading slot

Date：2014-07-30 10:10:27

Vertical injection molding machine with a threaded rod at both ends, one end of the triangle threaded rod and nut secured to the stationary platen, and the other end of the trapezoidal thread is used to adjust the position of the tone template to allow clamping mechanism can adapt to the needs of different mold thickness . Connecting rod is vertical injection molding machine set templates, dynamic templates and adjust the template to form a closed frame structure; clamping force to bear important bearing parts. Vertical injection molding machine in use, in addition to rod breakage occurred early in the first bearing tooth-root with its threaded coupling nut at the outside, threaded rod breakage will occur early in the last slot of the unloading.
         Impact of vertical injection molding machine for unloading tank trolley stress distribution on the trapezoidal thread, paper uses finite element analysis and optimization methods for parameter optimization analysis unloading tank, trapezoidal threaded rod to reduce stress in recent trough at unloading, so unloading tank really helps to reduce stress concentration effect avoid trapezoidal thread rod fracture occurred early in the last slot of the unloading.
         Stress analysis a trapezoidal threaded end of the original trolley
         1.1 Finite Element Analysis trapezoidal threaded rod ends
         Model in Figure 1, the rod-type trapezoidal thread embedded with AN SYS A PD L language drawn symmetrical and unloading tank, trapezoidal nuts tooth type and other two-dimensional geometric features, templates simplify the transfer rod is located on both sides rectangular block. In order to better mesh of small rounded trapezoidal thread at the root, where unified with 6 node triangular plane unit rod, trapezoidal nuts and adjust the template mesh.
         Set the tone at the top all-around lock template, template for fixing the tune; template and set about adjusting nut lateral restraint on both sides, so that the model will not spread when loading. Passed by the contact force between the parts of the nut and screw threads on the rod, the contact and exposure to adjust the template inside the outer edge of the nut and threaded rod end and adjust the bottom of the template implementation. Vertical injection molding machine trapezoidal threaded rod on the parameters and unloading tank for the original design value, namely 20 to fillet radius, the radius of the smallest difference with the basic thread groove radius is 2.S Inln, slot length of 70 ~.
         Actual use, 45 steel rod material after quenching, the elastic modulus of 2 06 G Pa, Poisson's ratio is 0.29, a yield strength of 3 5 MPa, a tensile strength of six field MPa; tune template material QT50, the elastic modulus of 173 G pa, Poisson's ratio of 0.27.
         Loading model is divided into two parts, one for the one-way node tensile stress: Trolley axial force is 5 87 so N, the value of the test results obtained by the strain after conversion, even tone template loaded in the bottom five from India Inm rod on the upper end node. The other is the lateral displacement: the whole rod and finite element analysis results template, template extraction rod between the tone arm with the word car, from 50 to adjust the template mounting holes at the cross-section of X and y displacement, in Integrated tilt adjustment of the bending rigidity of the template after the deformation, which is determined to obtain the real displacement of the X-and Y-direction, and then calculate the displacement vector of the two vectors and with a size of 0.536mm.
         The results 1.2 vertical injection molding machine trapezoidal threaded end of rod above the finite element model, using nonlinear contact algorithm augmented lag ra llge be calculated, under stress, such as rod and nut for the elastic-plastic material analysis results in partial loads .
         Among them, the rod and nut vertical injection molding machine parameters for the original design parameters. Extraction AN SY S results in the software, the relief groove can be obtained rod 2 nodes left in the middle in the longitudinal direction of the average strain 920 worship. The actual test is 949 fight strain compared with the measured values​​, the relative error of the calculated value of 3.06%. It can be seen, these finite element analysis model realistic trapezoidal threaded rod ends. Vertical injection molding machine of the original trapezoidal thread rod end in the partial re-action, the left and right sides of each tooth-root maximum stress curve. Located in the upper curve of the left side of the root of the threaded rod of maximum stress, the lower curve to the right of the threaded rod case maximum stress at the root.
         Among them, a positive number represents the thread of the nut with a threaded rod, a negative number represents the thread rod threaded rod and nut groove between unloading. From the above two curves shows that the left side of the threaded rod nearly unload slot 2 tooth-root, the maximum equivalent stress and the nut with a 12 tooth-root more than 3 5 MPa, that have had plastic deformation. Rod trapezoidal thread roots in the past, such as unloading effect at maximum power slot 378 MPa, and away from the unloading tank thread root maximum stress compared to the minimum 3 n MPa large 17.7%.
         For axial tension load only when the rod is still using the parameters of the original unloaded slots if trapezoidal thread parameters are optimized, the tank is nearly unloaded at a maximum stress of 2 04 MPa, and away from the root thread relief groove minimum 158 maximum stress MPa compared to the large 29.1%. From the above analysis, if the parameter rod unloading tank design is not appropriate, threaded rod unload stress in recent trough at large, easy to unload slot near the first thread root at the Ministry of cracks caused by rod fracture. Therefore, it is necessary to unload the groove corner, the minimum diameter and length parameters to optimize the threaded rod to reduce the stress in the last unloading of the tank to prevent the rod in the area of early rupture.
         2 vertical injection molding machine parameter optimization model trolley unloading tank
         Poor radius rod between the body and unloading tank is small, considering the convenience of processing, in the groove between the rod body and unloaded directly with rounded corners transition. To be able AN SY S of APD L language draw the rounded corners, in Figure 4, the first to make a slash, and then draw a connection largest FI LLET rounded rod body and unloading tank, where D is the relief groove line segment length.
         Radius rod body; TR minimum radius of unloading tank; X is transverse length slash. From the foregoing analysis, the stress relief groove in recent thread first and second tooth root portion may be greater. To control stress l tank thread first and second tooth root portion of the nearly unloaded without excessive axial tension rod at the same time, the need to bear the additional deformation template moment.
         4 unload slot constraints are used to control the maximum rounded clusters as a function of two R 3 (X) (8) Based on the above three objectives of the overall goal of optimizing the impact. Here maximum control with minimum radius rod slightly less than the value of the root of the thread.
         3 Rod unload slot parameter optimization results
Sequence analysis of this paper, the zero-order optimization method ANSY S software optimized nested calculations. To speed up the iterative process optimization, optimization model is loaded only in axial tension rod ends, without lateral displacement, axial tension by its nominal vertical injection molding machine clamping force loading, ie axial tension is 50. After 13 optimization calculations, obtaining optimal results: X = 13.5 654, D = 5.18 47, TR two 40.56. At this time, relief groove fillet radius R two 6 0.4 Inln. Vertical injection molding machine in the name of clamping force is Zo t, the trapezoidal threaded rod ends under axial tensile force equivalent stress distribution.
         Among them, nearly vertical injection molding machine to uninstall trapezoidal thread groove at the maximum equivalent stress is 158.7 MPa, between the optimized parameters than the thread relief groove and nut thread root maximum stress at minimum 8 MPa clever little larger, less than in the original design parameters under 329 MPa 52%; unloading slots at the maximum equivalent stress is a clever .1 MPa, the average value of 9 6.7 MPa uniaxial stress 20% higher than its big. The total length of the relief groove 6 3.2 6 mrn, slightly shorter than the original design length of 70 ~. After the vertical injection molding machine is measured at 235 t clamping force of circumstances, unloading tank with trapezoidal thread parameters optimized rod threaded end of the triangle under partial loads maximum stress curves for each tooth root.
         Which is located in the upper part of the curve is vertical injection molding machine at the left corresponding to each root trapezoidal thread maximum equivalent stress relief groove at its near maximum stress of 334 MPa, compared with pre-optimized 3 78 MPa reduced by 1.6% , but with the thread at the root of slot away maximum stress is larger. Unloading tank near the right side of the threaded rod at the root of each of the maximum equivalent stress is much smaller compared with the left, reflecting the threaded rod under partial loads force is uneven. This is mainly due to the smaller stiffness of a given template and adjust the position of the template holder unreasonable, resulting in the upper part of the template backward tilt adjustment is large, resulting in a large additional bending moment on the rod, leaving the threaded rod end produce significant partial load effects. To solve the problem of discontinuity threaded rod better, the need for each template structure and parameter optimization prisoners and improve its overall stiffness under the control of the total mass of clamping mechanism premise.
4 Conclusion
         Through the vertical injection molding machine unload slot multi-objective optimization parameters, the stress relief groove at the appropriate concentration at which the maximum stress than the average one-way tensile stress increased 20% vertical injection molding machine Rod trapezoidal thread root in nearly unloaded maximum stress at the lower 52% of the slot, you can better play the role unload unload slot; under partial loads, pull Gu trapezoidal thread relief groove at the root of the recent reduction in the maximum stress of 0.6%; while also reducing unloading groove processing capacity and reduce processing costs.
         Therefore, unloading slots should not be used to determine the parameters of empirical design methods should be integrated stress distribution and reduce the amount of processing a number of factors, such as the application of finite element analysis and integration of multi-objective optimization method to determine reasonable relief groove parameters. Vertical injection molding machine trolley nearly trapezoidal thread relief groove at more severe stress concentration due to: Uninstall groove parameters unreasonable, given the rigidity of the smaller template and adjust the position of the template holder unreasonable. The presence of stress concentration problems trapezoidal threaded rod vertical injection molding machine prone to an early break in the vicinity of the relief groove.

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