Tehtran - Sheet matherial nesting (true shape)

Tehtran software is a comprehensive solution for sheet material nesting, combining CAM capabilities with production engineering functions. The approach employed in Tehtran sums up the experience of a number of companies utilizing thermal cutting machines in their operations. algorizhm

Using the Database

The system integrates Tehtran’s conventional cutting programming tools with a database. Apart from providing data management, the database controls the entire operation of the system, because nesting programs are also database objects.

The first objects entered into the database are parts, which can be created using the tools provided by Tehtran or imported from another application. The parts are better viewed along with the list of all parts. To help manage parts and other database objects, Tehtran offers a single visual mechanism that uses two panes. This mechanism lets you manipulate database objects in the list (create, delete, edit, or view their parameters) while at the same time viewing the graphic representation of list items (parts, plates, nests, etc.) in the adjacent pane. In addition, having two panes available makes it easier to work with objects that, in turn, contain other objects. For example, a nest contains parts. To view parts belonging to different nests, you can display the list of nests in one pane and the list of parts nested on a specific plate in the other.

Nesting Jobs

Tehtran provides interaction of the various objects involved in the process of sheet material nesting. The parts that have to be manufactured form a job. Then, plates that will be used to manufacture the parts are added to the job. The system permits automatic and manual nesting of the parts in the job on the plates. In both modes, it keeps track of non-nested parts and checks whether a part can be manufactured of the selected plate.

Automatic Nesting

In automatic nesting mode, the system lays out the parts in the job on the plate in the optimum way. Any additional required plates can be automatically taken from stock. The system also lets you automatically nest selected parts on a specific plate while maintaining specified clearances to the plate edge and between the parts. The automatic nesting strategy ensures a sufficiently high material utilization ratio. You can select an optimum nesting quality to computation time ratio.

When nesting parts automatically, you specify how the parts will be concentrated on a plate that is not completely filled. This affects the shape and proportions of remnants with account for their further usage. Controlling the choice of parts for hole filling lets you nest smaller or larger parts in the openings inside other parts or leave the holes unfilled.

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tehtran_nest

Manual Part Nesting

In manual nesting mode, a part is selected from the list of non-nested parts and placed onto the plate, and then moved to a free space using the graphics editor tools. Tools are also provided for precise control of relative positions of the objects.Combining automatic and manual part nesting lets you leverage the advantages of each mode for the maximum efficiency.

Part Interference Control

In manual nesting mode, the system performs several useful functions for you. These include different methods of moving parts while maintaining required clearances between the parts and between the parts and the plate edge, and also the possibility to place parts flush to each other.
    Blocking interference control. When this function is on, you can move the parts on the plate on the display screen as if they were real life objects that cannot go across other parts and the edge of the plate.
    Warning interference control. When using warning control, movement of the parts is not limited to the free space of the plate. However, when a part is moved so that it overlaps other objects, it is highlighted in distinct color to indicate its intolerable position.
    Moving parts all the way to the edge. This function lets you position the part against the very edge of the free space of the plate. In other words, the part is moved all the way in a certain direction until it encounters another part or the edge of the plate.
    Copying parts flush to each other. When copying parts in this mode, the system automatically determines the distance by which the part can be moved in the specified direction so that the parts end up placed flush to each other.
    Aligning part edges can be used to orient the parts so that their selected sides adjoin.
    Aligning parts to a line. This option is useful when positioning the parts for through cutting.

Programming Cutting

After the parts are positioned on the plate, the cutting is programmed. In the simplest case, you only need to specify the contours of parts to cut in the correct sequence. The system then creates the toolpath incorporating necessary allowances, generates lead-ins, lead-outs and auxiliary motions of the tool, torch turn-on and turn-off commands, feedrates, compensations, etc.
    Lead-in and lead-out. Options are provided to configure various methods to approach the contour being cut (line, arc, normal, tangent etc.), as well as for lead-in point selection (automatic or explicit) and selection of torch modes at different cutting stages.
    Tabs. You can define sections of the part contour that should not be cut. They are called tabs. When creating the path, the system automatically generates torch turn-on and turn-off commands in such spots, and inserts lead-in and lead-out sections.
    Bridges between parts allow cutting several parts without turning the torch off. The points where the path passes from one part to another are specified after the parts are positioned, and are taken into account when creating the final torch path.
    Loops enable clean cutting of part corners, and can be added to any corner.
    Predefined cutting. To make your work easier, part cutting can be pre-programmed in order to avoid repeating the same actions to include the same items into the nest multiple times.
    Manual cutting. For special cases, Tehtran provides tools to explicitly build the toolpath and specify tooling commands.
    Subroutines provide structure to the output CNC code, and help reduce the amount of text generated.

Automatic Cutting

Automatic cutting mode makes programming cutting for a large number of parts as simple as possible. The system automatically assigns part profiling sequence and performs the cutting. Various part profiling strategies ensure that the required cutting conditions are respected.

Preparing Edges for Welding

Thermal cutting machines equipped with three-torch units can bevel part edges for welding. Tehtran lets you bevel the edges using both constant and variable bevels. A constant bevel has the same top and bottom angles and heights throughout its length; in a variable bevel, the angle and height change uniformly over the length. The program automatically incorporates special areas called bevelling windows into the torch path where the side torches are turned on, and adds bevelling loops to ensure correct orientation of side torches and respecting the required cutting conditions. Bevelling windows can be repositioned using the graphics editor.

Plate Marking

Plates can be marked using powder or punch. Marking contours can be stored in the database along with the part. In this case, the marking is nested on the plate together with the parts. To program the marking unit, you only need to specify marking contours in the correct sequence. The system will perform all necessary turn-ons/turn-offs and create the path.

Multi-Carriage Cutting

On machines equipped with several carriages, several parts can be cut simultaneously. Both automatic and manual nesting of parts can account for the capabilities of such machines. When programming cutting, the correct carriage layout is performed automatically.

Utilizing Remnants

Unused portions of the plate produce remnant plates that can be stored in the database for future use.

Documenting
The system generates the following output documents:
·   nest drawing
·   nest report
·   job summary report
Normally, the presentation of output documents depends on company standards. The report generator included in Tehtran provides a flexible mechanism for customizing the format and the level of detail for output documents.

Automatic Text Generation
While you create geometric object and design nesting, the system generates program text in the Tehtran language. The program includes the entire sequence of the actions performed, and can be used for future work. This enables flexible combination of easy-to-use interactive mode with the advantages provided by text representation of the program, such as:
·   Using previously written programs and macros and quickly modifying them as needed
·   Parametrizing standard parts
·   Using conditional statements, loops, arithmetic expressions and functions
·   Debugging and eliminating errors

Program Development and Debugging Tools
The system provides a set of tools to design and debug programs written in the Tehtran language:
Program execution commands (run a statement, go to a macro, run the program to the end, to cursor, etc.) allow you to run and debug programs written in Tehtran. Using these commands, you can run the program entirely or in portions, pausing to examine the result of executing individual statements.
Execution control tools enable examining the values of variables, using the graphics window to visually control the program’s objects, and viewing the diagnostic information generated while running the program.

Generating CNC Codes

The post processor built-in in Tehtran permits generating CNC codes for various NC machines using the part program and the machine data included with the system. A part program generated for one machine can be used to produce a CNC code for any other machine in the machinery list.

Setting Up for Specific NC Machines

Tehtran has the ability to be set up for specific NC machines. In order to define the machine, you need to fill in a machine datasheet and create a machine module in the special Tehpost language. This enables users to accommodate CNC code generation specifics for their particular environment by developing their own modules based on those provided.

System Requirements

·   Pentium III processor or compatible
·   Windows 2000/XP/Vista/7
·   300 MB RAM
·   100 MB free hard disk space
·   1024x960 screen resolution or higher, 256 colors