Building the SPM elements database

In order to build a database for SPM elements, it is important to consider the following factors:

 The category of each element.

 The supporting and supported faces of each element.

 The assembly features on the supporting and supported faces of each element.

 The geometric parameters of each element.

 The classification of each element with regard to its role in the SPM design.

With regards to the first factor, SPM elements are divided into four main categories: function, motion, supporting, and accessory elements. Function elements are used to perform machining processes such as drilling, milling, tapping, and reaming. Motion elements provide rotational and linear movements.

A linear movement is needed when function elements are required to move during machining processes, and it can be in one to four directions. A rotational movement is required to transfer the workpiece from one station to another in order to perform multiple machining processes. Supporting elements are needed to provide the positioning support for the function elements. Accessory elements

102 such as clamps, chucks, and multi-spindle heads are used to complete the design of SPM layouts. Regarding factors 2, 3, and 4, the assembly features and geometric information need to be defined and used to represent SPM elements in order to define the assembly relationships between these elements. In this work, eight assembly features were identified: supporting faces, supported faces, locating holes, counterbore holes, screw holes, fixing slots, pins, and screw bolts, as shown in Figure 4-3. A supporting face is the surface on an element that supports other SPM elements or the workpiece, while a supported face is the surface on an element that is supported by other SPM elements. A locating hole can be used as a locating point with a locating pin, while a counterbore hole and a fixing slot are used to join two SPM elements with screw bolts. In SPM elements, the assembly features are designed with standard dimensions and are perpendicular to the supporting or supported faces. These features are identified as associated assembly features with supporting and supported faces of the elements, and because the features have standard designs and dimensions, their positions and orientations are known.

Figure 4-3. The eight assembly features.

103 Some SPM elements have supporting and supported faces and they can be used to support an element, while they are already supported by other elements, as shown in Figure 4-4.

Figure 4-4. Supporting and supported faces for SPM elements.

The classification of SPM elements is based on their roles. Function elements are classified into MONO master, CNC master, TAP master, POWER master, and MULTI master. Motion elements are classified into sliding units and rotary indexing tables. Supporting elements are classified into horizontal, vertical supports, base plates, universal supports, and slide blocks. Accessory elements are classified into POLYdrill, TOOL holders, and machine components [124].

Figure 4-5 shows the main categories and classifications of SPM elements.

104 Figure 4-5. The categories and classifications of SPM elements.

By considering the above factors for building an SPM database, a linked list structure was developed in this work to represent SPM elements. This structure shows how the information is organised for each element with regards to its category, classification, number of supported and supporting faces, number and type of the associated assembly features, and geometric information. A general example of this structure is shown in Figure 4-6. This structure was used as a basis for developing the SPM database. Each element has a Record which contains information about this element at different levels and how these levels are linked. Figure 4-7 shows an example of the linked list structure for a function element (BEM 6). The SPM database was developed using Microsoft Access in this thesis and contains the necessary information for SPM elements. In addition, 3D models for these elements were designed and stored in a design library in SolidWorks to be used in performing the SPM assembly.

105 Figure 4-6. A general list data structure.

Figure 4-7. A data structure representing an BEM 6 element.

106

4.1.1 Microsoft Access database for SPMs

The information about SPM elements was used in this work to build an Access database. Microsoft Access is used to design and create databases for many applications. This is because it can deal with lists and tables of information.

Although there are other software programs that have features to create and manage lists and tables, Access is the only software program that can handle large quantities of complex information. Access has the ability to create multiple tables in a way that allows the information in these tables to be linked. This is a very effective feature when analysing and extracting data from multiple tables is required. Access also has very useful features such as the ability to create customised routines, print a variety of reports, and design fine-tuned forms for data entry. These features were used to build a database for SPM elements and each element is given a record, which includes the following information:

 Element ID.

 Element name.

 Element classification.

 Element geometric information.

 Number of supported faces.

 Number of supporting faces.

 Number of associated assembly features (screw holes, locating holes, counterbore holes, and fixing slots).

The process of establishing the database starts by creating a table for each category of SPM elements. This facilitates the use of the database by entering new information or by modifying the existing information, and four tables are created: Function Elements, Motion Elements, Supporting Elements, and Machine Components - Accessory Elements. Each of these tables contains the information listed above for each element in the related category. Figure 4-8 shows an example of a table for function elements.

107 Figure 4-8. A table for function elements in the SPM database.

Each type of information has a specific field (column) as shown in Figure 4-8. The information for each SPM element is identified and entered in the right table for a specific category. Multiple tables can be opened at the same time so the user can browse and access the information in these tables. Additional figures about SPM Access database can be found in Appendix 9.7.

4.1.2 The design library of SPM elements

The information provided in the tables is not sufficient for the SPM assembly process, and 3D models for SPM elements should also be designed and stored to be used in performing the assembly process. These models are also important to provide a complete picture of how SPM elements are assembled using the information of the assembly features information in the database. SolidWorks was used in this work as the modelling software to design 3D models for SPM elements and to perform the assembly process for these elements. The 3D models were created in the Part modeller (Part document) and stored in the design library in SolidWorks. The design library has the ability to organise SPM

108 elements in categories by creating new folders for each category. Figure 4-9 shows the design library in SolidWorks and the created SPM folders.

Figure 4-9. Creating the SPM folders in the design library in SolidWorks.

For each element, a 3D model was designed and added to the relevant folder.

Figure 4-10 shows an example of an SPM element designed in SolidWorks and added to the design library. A significant amount of effort has been put into making the large number of 3D models of the SPM elements required in this work, and some models that are downloaded from corporate websites have also been used. The availability of 3D models for SPM elements is important to determine the assembly relationships between these elements and this helps to create the assembly graph and the assembly relationships database for SPM elements.

109 Figure 4-10. (a) A machine base designed in SolidWorks and (b) adding this element to

the design library.