The role of fasteners is to fasten and connect mechanical parts. Its applications are extremely extensive. It is characterized by a wide variety of specifications, different performance and uses, and a high degree of product standardization and serialization. At present, most enterprises have created a standard parts library (including fasteners), but still use manual assembly methods during assembly.
This traditional assembly method has the following disadvantages: fasteners are stored locally or in designated locations on the server, and the user selects them as needed when using them. For the case where the standard parts library level is more complicated, it is necessary to search step by step, and it is difficult to select the type; the fasteners are not assembled in groups, and they need to be assembled one by one, and to complete the assembly between every two components, at least two need to be defined Constraint relationship, cumbersome operation, and low efficiency; when the specifications of the assembled fasteners are modified or deleted, they need to be operated one by one, which is inefficient and does not meet the design habits; the fasteners are generally drilled before the holes are assembled. The fastener specifications are not related to the screw hole size, and cannot be updated synchronously when the design is changed; the combination method and cooperation method of the fastener need to query the relevant standards or the mechanical design manual, which is inconvenient for the accumulation and transmission of the commonly used fastener knowledge of the enterprise.
This article takes the three-dimensional CAD software Pro/E as the object, does some research on the fast automatic assembly technology of fasteners, and gives the realization method.
The fastener tool is customized for the enterprise, and its basic data comes from the enterprise's standard parts library. The main function is to meet the needs of enterprise customers in the fastener design process, can easily find and call enterprise standard parts, and supports grouping, batch assembly, modification and deletion of fasteners, thereby saving time and improving design efficiency. The specific requirements are as follows: The system belongs to the secondary development tool, and the advanced software architecture should be adopted to ensure the stability, reliability, scalability, and ease of maintenance and upgrade of the system performance; the system should be seamlessly integrated with the 3D CAD design software and does not affect the 3D CAD Use of design software. In addition, if the enterprise's standard parts library is stored in the PDM system, the tool must also be integrated with the PDM system in order to read the fastener information under the specified path; in order to facilitate the management of fasteners, the enterprise standard must be first The parts library is sorted out, and the commonly used fastener specifications, matching methods, combination methods, etc. are provided; a visual and integrated program interface is provided, and different options can be displayed on the interface in real time, which can intuitively express the assembly effect; automatic recording The last operation information is convenient for repeated operations.
Quick type selection is to quickly select the required fasteners from the specified standard parts library. The basic idea is to use the program to automatically read the information of the standard parts library under the specified path, and through the graphical interface to the standard number, specifications, Attribute parameters such as performance level, surface treatment, material coding, etc. are screened and queried, and the program automatically obtains a matching fastener model based on the selected fastener information.
This wizard-type selection method can not only quickly select the required fasteners, but also effectively manage and effectively control the fastener specifications commonly used by enterprises.
In addition, in order to enhance the automation of attribute parameter selection in the assembly process, this paper also studies and realizes the automatic matching function of the parameters of bolts, nuts, washers, etc., that is, when the user selects the nominal diameter of a bolt, according to the accuracy level of the hole and the According to the different matching methods, the system automatically filters out the parameters of nuts and washers that match the nominal diameter of the selected bolts in the read standard parts library information table, so as to realize the rapid selection and update of the matching fastener group.
The realization of group assembly is one of the key technologies of fastener tools. The core idea is to define the matching fasteners in groups in the assembly model.
Generally, according to the different types of main drive parts, the fastener groups can be divided into three categories: bolts, screws, and nuts, and according to the different main drive parts, many different combinations can be defined. For example, some combinations require the installation of elastic pads and flat pads at one end, some combinations have elastic pads and flat pads at both ends, and some combinations also have thin nuts at the ends. The combination method can also be edited as needed. After editing, it can be added to the list to facilitate repeated operations.
In order to facilitate the designer's viewing, the selected fasteners are rendered according to the selection in the form of graphical preview (unselected fasteners are highlighted), which can intuitively express the effect of the assembly, as shown.
In addition, in order to improve the efficiency of assembly, the software has also studied the functions of batch assembly, quick U-turn and batch deletion.
1) Mass assembly function: In one assembly, for fastener groups of the same specification and the same matching method, it is often necessary to assemble multiple times. The program automatically places fastener sets in batches by finding the same hole feature.
Combination method 10 Bolt 0 Upper flat washer 1 Upper elastic washer 0 Lower elastic washer 0 Lower flat washer 0 Nut 0 "Thin nut is added to the list Fastener combination method Mechanical industry standardization and quality Step 6S inch W" inch 2>Quick turn function: Rotate the selected fastener group as a whole by 180. and exchange the (mating surfaces) at both ends (bolt side and nut side) of the fastener group, thereby changing the installation direction of the fastener group.
3) Batch delete function: For unneeded fastener groups that have been assembled, a dialog box will automatically pop up when deleting, prompting the user whether to delete the same batch of fastener groups, and carry out the characteristics of the same batch of fastener groups Highlight as shown.
Automatic hole drilling technology is one of the difficulties in the realization of fastener tools. Traditional assembly methods generally pre-open holes before assembling fasteners, and hole features are often established at the part level, so that there is no association between hole features and fasteners, and cannot be updated synchronously when design changes. You need to manually modify them one by one. The operation is very cumbersome.
First, the program obtains the position of the hole through two interactive operations by the user, one is to select the position of the datum point or datum axis, and the other is to select the two ends of the fastener group.
Then, set the hole size and accuracy (generally including coarse, medium, and fine) through the interface to control the size of the hole, as shown in the selection of "hole data" hole data hole point axis selection hole diameter bolt side nut side automatic hole drilling The selection of the diameter of the cylinder and piston rod of the high vacuum pneumatic baffle valve Shenyang Ruifeng Technology Co., Ltd. □ Huang Bojian determines the method for the selection of the diameter of the cylinder and piston rod of the high vacuum baffle valve.
The vacuum valve is a component in the vacuum system used to adjust the gas flow, cut off or connect the pipeline. The high-vacuum baffle valve is powered by compressed air, changes the direction of the gas path through an electromagnetic directional valve, and performs the opening and closing movement of the cylinder-driven baffle valve. It is suitable for 1.3x14Pa~1.0x105Pa vacuum system to open or block the air flow. The baffle valve has the advantages of simple structure, short opening and closing time, safe and reliable, strong and durable, and can be automatically controlled. It is widely used in electronics, chemical industry, metallurgy, aviation, aerospace, materials, biomedicine, atomic energy, cosmic detection, etc. Science and technology. The design of the cylinder diameter and piston rod diameter of the high-vacuum pneumatic baffle valve is very important. When the baffle valve is opened and closed, if the diameter design of the cylinder and piston rod is not reasonable, it will cause problems that the valve cannot be opened and the opening and closing time is long. This article describes how to estimate the diameter of the cylinder and piston rod at a given pressure to provide a solution to this problem.
Check the calculation of the specific pressure of the sealing surface of the baffle valve cover. This article uses an atmospheric pressure, nominal diameter DN160 high vacuum pneumatic baffle valve as an example to calculate, see and Table 1. Mechanical industry standardization and quality. In addition, the fastener group will automatically Record the hole feature information matched with it. When the position of the fastener group moves, you can automatically modify the feature size of the hole matched with it by updating the program.
Reasonable selection of secondary development tools and languages ??is the key to program portability. Pro/TOOLKIT provided by PTC for Pro/E is a powerful secondary development tool for Pro/E. It encapsulates many library functions and header files called for the underlying resources of Pro/E. You can use a third-party compilation environment (C Language, VC++ language, etc.) for debugging. Pro/TOOLKIT provides seamless connection with Pro/E for user programs, software and third-party programs.
It enables external applications to access Pro/E's databases and applications safely and effectively. Through the C language programming and the seamless integration of the application and Pro/E, users and third parties can add the required functions in the Pro/E system. Therefore, fastener tool software is developed in combination with VC++ and Pro/TOOLKIT.
According to the ideas of group assembly and other ideas, using Microsoft Visual C++ for programming, fastener tools that meet the assembly habits have been developed on the 3D CAD software Pro/E platform, which realizes the rapid selection of fasteners, group assembly and intelligent drilling And other functions, and can be used in fastener design work. Practice has proved that the tool has a significant effect on improving the design efficiency of fasteners, which is convenient for the accumulation and transfer of knowledge of fasteners commonly used by enterprises.
