Research and application of mold parting method ba

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Research and application of mold parting method based on UG

1 preface

in recent years, three-dimensional CAD technology has been widely used in the field of mechanical engineering, especially in mold design and manufacturing, it is also a right-hand assistant for designers, which effectively improves work efficiency and reduces labor intensity. Among many 3D CAD software, UG has occupied a leading position in the industry for a long time with its powerful functions

The mold wizard is an intelligent and parameterized injection mold design module running on the basis of Unigraphics NX software. It provides a convenient and fast design way for mold design. Finally, it can generate 3D mold related to product parameters and can be used for NC machining, and can automatically carry out difficult and complex mold design tasks. It can help users save design time and provide complete 3D models for processing. If the product design changes, it will not waste any more time, because the change of the product model is completely related to the mold design. In the three-dimensional design of injection mold, the key technology is parting, while other features are relatively simple and easy to solve

mold wizard parting principle is to use the cutting surface composed of the parting surface of the product model and the outer surface of the product model, so it is difficult to clamp to separate the molding insert, so as to separate the cavity parts; Use the cutting surface made of the parting surface of the product model and the inner surface of the product model to divide the molding insert and divide the core parts. This paper will introduce the method of using UG software to create the core and cavity of the mold through a typical example of the end cover part

Figure 1 two dimensional mechanical drawing of parts

2 mechanical structure of end cover parts

two dimensional mechanical drawing of parts is shown in Figure 1

by analyzing the two-dimensional mechanical drawing of the part, we found that the upper end face of the mechanical part has a circular hole, a circular hole and a hollow column, the bottom circumference has 6 threaded holes, the wall thickness of the part is 5mm, and the definition of the core and cavity area is the difficulty of the part's parting

Figure 2 UG modeling drawing of parts

use UG nx4.0 software to draw the three-dimensional modeling drawing of parts, as shown in Figure 2

The basic process of mold wizard mold design can be divided into project initialization, initial preparation stage, mold design stage and post-processing stage

3.1 add product and project initialization

when using the mold wizard to design the product mold, the first thing to do is to load the product and project initialization to produce a mold assembly structure composed of the necessary standard elements of the mold. Open UG nx4.0, click the "injection mold Wizard" button in the "application" toolbar to enter the "mold Wizard" interface. Load the product, input the file storage path and file name, and select the plastic name used by the part as ABS

3.2 define mold coordinate system

mold coordinate system is the coordinate system used in mold design. Click the "injection mold Wizard", pull the "mold coordinate" button in the button, and select the "current WCS" button to complete the setting of the mold coordinate system

3.3 set the shrinkage stroke

the shrinkage caused by the solidification of liquid plastic into homomorphic plastic products, which is used to compensate for the scale factor of part shrinkage. Click the "shrinkage" button in the "injection mold Wizard" button, and enter the corresponding value in the pop-up "proportion"

3.4 define part forming inserts

a single formed part module before parting is called a formed insert, which is referred to as rough embryo for short

the molding insert definition function provided by the mold wizard will automatically measure the overall dimension of the part and establish a punch insert and a female insert of the default size. Click the "workpiece" button in the "injection mold Wizard" button to pop up the "workpiece size" dialog box, and enter the corresponding value

3.5 product model repair

Figure 3 defines the cavity and core area of the part

before the molding insert is divided into core and cavity, if there is a through hole or notch on the plastic part, so that the cavity side and core side are connected, the through hole or notch must be repaired. After selecting the "set area color" option in "model component verification", figure 3 is obtained, in which the yellow area represents the cavity; The blue area at the bottom is the core area; The cyan area on the bottom circumference has not been defined as the core or cavity. Considering that we will select the bottom end face as the location of the parting surface, we designate it as the cavity area

Figure 4 patch of parts

when creating a mold cavity in a solid model, you often encounter some holes or other mechanisms that will affect the promising parting process in the Zhengxin material industry, requiring users to create some surfaces or entities for repair. If there is a through hole or notch on the plastic part, so that the cavity side and the core side are connected, if it is not repaired, the parting sheet will not be able to divide the molding insert, and the system cannot identify whether the through hole or notch belongs to the cavity side or the core side. By clicking the "automatic repair" option in the "patch ring selection" menu, the result after the part patch is shown in Figure 4, in which the milky white area is the patch body formed after the patch

3.6 create parting line

the parting line of the product model refers to the intersection line of the inner and outer surfaces of the model. The parting line extends outside the molding insert to form the parting surface of the product model. When parting the mold, first search the parting line, then create the parting surface, and then use the core trim sheet and cavity trim sheet to divide the molding insert, so as to obtain two independent core and cavity inserts

parting line refers to the boundary line between plastic and mold. The parting line of carbon/carbon composite products can be related to the shape of parts (at the maximum interface) and the direction of demoulding. According to the parting direction, mold wizard can search the possible places of parting and determine a more reasonable parting line. Select the option of "automatic search of parting line" in the "parting line" menu to automatically search the parting line of parts, avoiding the trouble of manually searching for the parting line

3.7 create parting surface

plastic solidifies in the mold cavity to form plastic parts. In order to take out the plastic parts, the mold cavity must be opened, that is, the mold is divided into two parts, namely, the fixed mold and the moving mold. The parting surface is the contact surface between the moving mold and the fixed mold of the mold. After the mold is separated, the plastic part or the pouring system can be taken out. Select the "create runoff surface" option in "create runoff surface", and UG software will automatically search the runoff surface of the concave convex die of the part

3.8 create core and cavity

parting is the process of generating cavity and core based on a plastic part model. Parting process is an important part of plastic mold design, especially for parts with complex shapes. Through the key automatic tools, the parting module can make this process very automated

search the parting line of the product model. After creating the parting surface, use the cavity trim sheet and core trim sheet to divide the molding insert respectively, and obtain two independent cavity parts and core parts. The created "core" and "cavity" are shown in Figure 8 and Figure 9 respectively

4 conclusion

in the whole three-dimensional design process of injection mold, parting is a very critical step, which requires not only the flexible application of relevant modules of UG mold wizard, but also rich design experience. Through a typical example of end cover parts, this paper explains Ding Li's method and steps of mold parting with UG mold wizard. Choosing a reasonable parting surface can provide a correct three-dimensional model for the subsequent solid-based NC machining, so that the moving and fixed surfaces of the injection mold have a good machinist. Adding carbon fiber can be used to enhance the conductivity and processability

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