Most match oil machine cylinder head lost foam cas

2022-08-06
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Cad/cam for lost foam casting die of diesel engine cylinder head (Part 1)

1.1 establishment of product model of single cylinder small diesel engine cylinder head. (1) The design modeling idea takes the design basis of the part drawing as the basis of the product model, and adopts the techniques of block modeling and overall assembly (Boolean operation). First, select the main model, that is, the main frame of the product model, that is, the main shell of the cylinder head as the main model; Secondly, each entity part other than the main model is modeled as a matching small module, that is, the bottom surface, top surface, fuel injector, intake port, exhaust port, support seat of intake and exhaust ports, and bolt boss entities of the cylinder head are used as matching small modules. The spatial relationship between the main model and the matching small module is unified in the design basis of the part drawing. (2) Application of the working coordinate system the working coordinate system refers to the Cartesian coordinate system, the effective right-hand rule for drawing graphics. When drawing effectively and quickly, it can move, rotate and store, so that the drawn lines are always in the plane of X-Y coordinate system, the stretching and rotation of feature entities are always along the direction of Z axis, and the rapid positioning function of working coordinate system is realized. (3) The management layer of the work layer refers to the effective picture space of the current drawing, with a total of 256 layers. The effective and flexible use of work level management can make the modeling ideas clearer and the lines and entity modules orderly. The specific operations are as follows: place the original lines of each matching small module and the main model on different working layers in order, and give each layer an image layer name in a readable and easy to remember language. Store each entity module made from the original line system of each layer on different working layers, and give the corresponding layer name. In this way, each component can be called and used in the final assembly (Boolean operation) of the mathematical model. (4) The setting of modeling accuracy is in the middle of each sub module of the mathematical model, including both feature modeling module and free-form surface (non feature) modeling module. If the modeling accuracy is not set pertinently during modeling, it will often lead to errors in Boolean operation between feature modeling module and free-form surface modeling module, resulting in modeling failure. Therefore, the accuracy of free-form surface modeling should be 1 ~ 2 orders of magnitude higher than that of feature modeling. (5) Establishment of product model the special high temperature endurance testing machine for thermal insulation profile can establish the cylinder head product model based on the part drawing, guided by the modeling idea, and taking the application of the working coordinate system, the management of the working layer and the setting of modeling accuracy as technical means

1.2 design of casting model and cutting of die

(1) the design of casting model scales the cylinder head product model, enlarges the product model by 1.013 times, sets machining allowance on the enlarged model, and uses modeling techniques to build a solid with machining allowance (2mm here) on each machining surface, which is superimposed with the model. Finally, the casting fillet is modeled. Thus, the casting foam model is established. (2) The cutting of the mold piece is based on the mold making method of the mold making machine (our company uses the horizontal parting method, the upper and lower mold pulling method) and the model structure. In order to facilitate the mold pulling, the gluing and the overall beauty, the cylinder head casting foam model is cut into four pieces, as shown in Figure 1

Fig. 1 casting model (cutting distribution diagram of once distributed mold pieces)

1.3 design the mold cavity and template structure

(1) design the mold cavity to distribute the mold pieces cut from the casting foam model twice to make them become a part of the upper and lower template cavities respectively. First, CAD is used to make the twice distributed cutting parting surface. The specific method is as follows: for the part of the die that can be completely lifted up or down, the die at this part can be cut directly, and the local cutting parting surface used for cutting can be obtained; For the part of the die that cannot be taken along the single direction on the die, the maximum contour line of this part of the die must be found out, and the cutting parting surface shall be made according to this contour line, so that the die cut by this cutting parting surface can be used to start the die in the upper and lower directions respectively; Finally, according to the machining characteristics, the transition parting surface and the template parting surface are designed to connect the local cutting parting surface. The local cutting parting surface, the transition parting surface and the parting surface are stitched together to obtain the cutting parting surface for twice distributing the die. Secondly, the module is subtracted from a solid square billet with a moderate size, and then the subtracted square billet is cut by twice distributing and cutting the parting surface to obtain the corresponding upper and lower template cavity structure 7: the post fracture structure of the sample. (2) Design the formwork structure, and standardize the peripheral dimensions of the upper and lower formworks according to the specifications of the mold mounting plates on the upper and lower steam cabinets of the molding machine. The support structure of spray gun, air plug installation hole, air overflow groove, air overflow hole, template installation bolt hole, template positioning sleeve and guide sleeve installation hole are designed on the upper template. The air plug installation hole, air overflow groove, air overflow hole, template positioning pin and guide pin installation hole are designed on the lower template

1.4 design gluing template

gluing template is used for die gluing. During the design, the surface sheet metal can be extracted from the die joint surface first, and the surface sheet metal can be cut to make the peripheral bonding width of the die 2.5mm, and the excess adhesive surface can be cut off. This can not only save the use of glue, but also prevent the excessive gap of the casting when the excess glue is extruded. Then stretch and cut the gluing surface into a solid body, and correspondingly design a support plate at the bottom of the solid that is consistent with the mounting plate of the gluer, as shown in Figure 2. (here, the cutting surface used for stretching should be reduced by 1.012/1.013 times)

Figure 2 die plywood "Zhang Weihua, the section chief, told us that the design of the template is to support and adsorb the die to facilitate the dipping of the die joint surface. When designing the template, the corresponding manufacturing template of the template can be reduced by 1.012/1.013 times. The periphery of the template shall be trimmed according to the specifications of the template support on the gluing machine, and the parting surface in the mold cavity shall be milled off by 2mm to make the joint surface of the template protrude and prevent the template from adhering to excess glue. Finally, the mounting hole of the vacuum adsorption nozzle is designed

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