Research and development of the hottest high speed

Research and development of high speed cutting process database (Part 1)

high speed machining (HSM) is one of the modern advanced manufacturing technologies. It has the outstanding advantages of high cutting efficiency, low cutting force and heat borne by the workpiece, low cutting forced vibration and high machining quality

its cutting speed, feed speed and feed acceleration are increased to 5 to 10 times that of ordinary cutting speed, and the technical data of machine tools, cutting tools and cutting processes are very different. Because the brand and performance of domestic workpiece materials are different from foreign conditions, it is not possible to completely copy foreign HSM process technical data. In order to give full play to the utility of expensive imported HSM equipment and prolong the tool life as much as possible, it is urgent to research and develop HSM process database suitable for national conditions, so as to provide practical reference tools for domestic enterprises as soon as possible. The following describes the high-speed cutting process database developed through international industry university research cooperation

Figure 1 framework of database system

1 function and basic structure of database system

the function of database system is to provide process technology data query information for users' actual HSM reference. High speed milling accounts for 80% of HSM applications. Therefore, currently, only milling technology data are included in the database

as shown in Figure 1, the database system includes software and process technology data

the software design adopts the current mainstream tree structure relational database, which is compared with hierarchical data or network data model It has clear mathematical foundation, strong management function and good operability. The software consists of two parts: background database and user interface. The former is various tables used to load the corresponding process and technical data, including the geometric information of the workpiece, and the latter is a set of man-machine dialog boxes between the former and the user

the user interface connects with the background database through the open database connection (ODBC) interface developed by Microsoft. ODBC is designed according to SQL rules and can be used as a general interface between various Microsoft programming languages and all database development platforms that accept SQL rules

hsm process technical data is partly accumulated through experimental cutting in our laboratory, and the other part is provided by Chinese cooperative enterprises participating in international cooperation projects, which is the crystallization of their production practice for many years

2 the background database of the software

according to the functions specified for the database system, it needs to include workpiece materials, tools, cutting processes and other data information of HSM cutting examples for future reference. Accordingly, tables such as workpiece materials, tools, processes and process pictures need to be established in the background database to store these information, as shown in Figure 2

Figure 2 logical structure of data information table

among them, the material of the processed workpiece has a global impact on the HSM process; Once the workpiece material changes, the tool material and cutting process parameters may change with it. Therefore, when determining the logical relationship between database tables, it is guided by the workpiece material table, which leads to the process table, which contains the columns of tool material and brand; Through them, the detailed information data of the tool is further derived

considering that the geometry and size of the workpiece also have a great impact on the HSM process, a process picture table is set up in the background database to indicate the geometric information of the workpiece corresponding to the cutting example, so that all the data information has more reference value. The process picture table also belongs to the process table

in order to accurately describe and define the processed workpiece material, in addition to knowing its name and brand as the basic identification, we should also give its hardness, tensile strength, yield strength, impact value, thermal expansion coefficient, elongation and other mechanical property index values; Their size, by affecting the cutting force and cutting heat, will have a great impact on the HSM process. Accordingly, the corresponding columns are set up in the workpiece material table

according to practical experience After determining the workpiece material, choosing different tool materials and grades will decisively affect the setting of cutting parameters and other technological conditions. Therefore, the column of tool material and brand is arranged at the beginning of the process table. Considering the situation of Dao, what should we do? First of all, it is very important to confirm whether the material at this position can be treated for rust prevention. The geometric parameters and structural performance information of the tool are many, and in turn will be restricted by the workpiece geometry and processing technology. Logically, it should not be juxtaposed with the process data information. A tool table is set up separately in the background database, which is subordinate to the process table

the column content of the second sequence in the process table is that when the HSM NC milling machine is actually operated, it is necessary to directly set the adjusted cutting parameters, that is, the spindle speed, axial cutting depth, feed speed, radial cutting depth, that is, the tool travel distance. As the cutting speed is a representative process parameter of HSM, and the feed rate per tooth of milling cutter is also an important cutting parameter, corresponding columns are added in the process table, which are converted by the background database to display and provide reference. In addition, columns describing other process conditions such as cooling and lubrication are also set up

hsm is mainly used for half tip and tip machining of steel and difficult cutting materials, as well as all rough and finish machining of free cutting materials such as aluminum, copper, engineering plastics and graphite. In order to take into account the diversity of processes, the process tables in the background database are classified according to rough machining and finish machining, and two columns of machining accuracy and surface roughness are added to the latter

the last column in the process table is the process picture number, which is used to export the process picture table and link the process technical parameters with the geometric information of the workpiece to be processed. In the table of process pictures, the identification of plasticization degree depends on experience. There are only two columns: process picture number and process picture. The former is linked with the process table, and the latter points to the physical address where the process picture is placed. The picture is displayed only when the user calls it

in the tool table, the first two columns are tool material and brand It is also linked with the process table. Then, according to the actual needs, a total of more than ten columns are set up in terms of tool name, geometric and physical parameters, use restriction parameters, composition and manufacturer and supplier, which can be increased or decreased at any time in the future

Figure 3 material table under SQL Server2000 platform