Stress analysis of vertical injection molding machine (one)

Date：2014/7/7 10:34:03

Introduction
         Vertical injection molding machine are heavy duty equipment, which is the main rod bearing parts and templates. Many vertical injection molding machine manufacturing enterprises due to the experience of the design are still using the traditional method, its vertical injection molding machine with a template prone to early rod breakage or cracking phenomenon early in the course, to bring a lot of direct and indirect economic loss. In this paper, the finite element method as a means for the characteristics of vertical injection molding machine toggle levers and templates to create the geometric model and finite element model consists of components such as rod and templates constituted to conduct stress analysis, and the analysis results proposed design improvement suggestions.
         Establish a rod and three-dimensional geometric model template
         UG is applied first feature modeling software to build three-dimensional graphics rod, fixed templates, dynamic templates, templates and word tone arm and other parts of the car. To reduce the number of grid finite element will simplify the threaded end of a cylindrical rod ends Rod with round table instead of the nut; ignored given hole templates, dynamic templates and tone template, cooling water holes and threaded holes installation Die other local minutiae, keep the main load-bearing part of the ribs and rounded corners. Taking into account the relief groove at the tune of nearly vertical injection molding machine trolley stress template features a large, labor-true model drawn carriage arm, in order to study the stress relief groove at. Requiring partial breakdown of the grid, on the moving platen and adjust template-assisted contact with the bearing block loads applied at the set. Because each template with the phantom symmetrical structure, the ideal state of its force is also symmetrical, whichever half for finite element analysis, will draw all the good parts are assembled into a whole structure in the UG environment and transformed into output format PARASOLID to prepare for redeployment and use of ANSYS.
         2 vertical injection molding machine with a template whole rod finite element analysis model
         2.1 Meshing
         Fixed template, material moving template, templates, and tune the car arm of the word are ductile QT500, the elastic modulus of 173 GPa, Poisson's ratio is 0.27, the auxiliary block also uses this setting, rod and other parts 45 # steel member, an elastic modulus of 206 GPa, Poisson's ratio of 0.29. For auxiliary blocks, respectively, using Boolean operations GLUE movable platen and the rear platen and bonded together, so that the load on which force can be entirely transmitted to the corresponding template. Rod and three-dimensional geometric model is more complex templates to SOLID92 meshing as a unit type, separately for each part, and the auxiliary block mesh. Given template assigned 18,915 units, the number of nodes is 30927; dynamic template assigned 31,835 units, the number of nodes is 52146; tune template assigned 36,466 units, the number of nodes is 56451; the rod allocated 24,156 units, nodes is 36326; under rod allocated 23,851 units, the number of nodes is 35919; workers carriage arm assigned 32,095 units, the number of nodes is 49,399; number of units assigned to other parts of the auxiliary block is 12807, nodes is 25711. The number of units for the entire model using a total of 180,125, the number of nodes to 281,559, in line with the requirements limit the number of units ANSYS FEM.
         2.2 in contact with the constraints on the set
         With Con tact Pa ir module defines the contact surface between the parts. Among them, the mating surfaces of each template with the word car arm and other parts of the set target surface, corresponding to the contact surface of the surface is set. In addition to the coefficient of friction contact surface of the phantom and the template is defined as 0.1 than the other contact surface due to the vertical injection molding machines are used in the process of using oil lubrication, the friction coefficient is defined as 0.05. Between the bottom and the rack is bolted fixed template, which is defined at the bottom of the template for the whole set constraints, bottom rail and the guide block is also set to fully constrained state. Each template with the phantom force in terms of geometry and symmetry in the geometric symmetry plane of symmetry constraint set. Stepped bore the word car arm set at Z to the constraint that the word trolley car along the longitudinal direction of the arm is fixed.
         Applying a 2.3 vertical injection molding machine load
         Vertical injection molding machine with a template as a whole trolley load is applied to a model of the auxiliary block set on the moving platen surface and adjust the template map, the load is transferred from the holder mounted on the moving platen and adjust the template on the clamping force to these surface. The vertical injection molding machine to toggle clamping mechanism, while clamping, toggle back and forth in a straight line, and the angle between the horizontal line of 4b. In order to facilitate load bearing surface element nodes, the role holder will be left on the moving platen force perpendicular to the moving platen decomposition auxiliary block bearing surface of the forward pressure component and tangential force component. Among them, the positive pressure decomposition of the force acting on the bearing surface relative to the center and the center of the moment. Assuming the role of the force in the center of the bearing surface is P, evenly distributed over the surface of the node stress Rj, then Rj = Pbh = 29 45MPa (1) wherein:. B is the width of the actual bearing surface, h is the actual bearing surface height. Acting in the center of the bearing surface of the bending moment M, then M = Qh2-h2Rw by dy (2) wherein the bearing surface of the bending moment M Rw y induced stress, and the linear distribution in y.
         It should be noted here is: on the block for auxiliary motor templates for vertical injection, its origin as the center piece of the template-assisted movement, namely the center of the force moving platen surface; For vertical injection molding machine auxiliary block to its y the opposite direction. Can be set Rw = ay (3) where, a is a constant. The formula (3) into equation (2), there are M = 112abh3 (4) by the formula (4) solve for a = 12Mbh3 = 168. 88 @ 106 Consolidated (1) and (3) we can get moving template-assisted block bearing surface stress distribution Rd = Rj + Rw = 29 45 + 168 88 y (5) template-assisted cutting move to block bearing surface force Fd = -.. 80 416 N Similarly, we have adjusted the template shear stress distribution on the surface of the auxiliary force bearing block respectively Rt = Rj + Rw = 35. 26 + 405. 30 y (6) Ft = 80 416 N at load bearing surface of the block template-assisted stress distribution and tangential force in two steps, first add the stress gradient load, Hou Jiaqie force loads. Write the load step file is loaded with every step LSWR ITE command to read progressively load step file when using the finite element method LSSOLVE command.

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