You can write control programs on a computer in a notepad, especially if you are good at mathematics and have a lot of free time. Or you can do it right on the machine, and let the whole workshop wait, and you don’t mind the extra workpiece. There is a third way of writing - a better one has not yet been invented.
A CNC machine processes a workpiece according to a G-code program. G code is a set of standard commands that CNC machines support. These commands contain information about where and at what speed to move the cutting tool to machine the part. The movement of the cutting tool is called a trajectory. The tool path in the control program consists of segments. These segments can be straight lines, circular arcs, or curves. The intersection points of such segments are called reference points. The text of the control program displays the coordinates of the reference points.
Example program in G codes
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Program text |
Description |
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Set the parameters: processing plane, zero point number, absolute values |
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Calling tool number 1 |
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Spindle activation – 8000 rpm |
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Fast travel to point X-19 Y-19 |
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Accelerated movement to height |
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Linear movement of the tool to the XZ point Y3 with feed F = 600 mm/min |
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Moving the tool along an arc of radius 8 mm to point X8 Y3 |
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Spindle shutdown |
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Completing the program |
There are three methods for programming CNC machines:
- Manually.
- On a machine, on a CNC rack.
- In a CAM system.
Manually
For manual programming, the coordinates of reference points are calculated and the sequence of movement from one point to another is described. This can describe the machining of simple geometries, mainly for turning: bushings, rings, smooth stepped shafts.
Problems
Here are the problems encountered when a program is written on a machine manually:
- For a long time. The more lines of code in the program, the higher the complexity of manufacturing a part, the higher the cost of this part. If the program contains more than 70 lines of code, then it is better to choose another programming method.
- Marriage. We need an extra blank for implementation to debug the control program and check for overcuts or undercuts.
- Equipment or tool failure. Errors in the text of the control program, in addition to defects, can also lead to breakdown of the machine spindle or tool.
Parts for which programs are written manually have a very high cost.
Rack-mounted CNC machine
On the CNC rack, the processing of the part is programmed online. The machine operator fills out a table with processing conditions. Indicates which geometry to process, width and depth of cut, approaches and departures, safe plane, cutting modes and other parameters that are individual for each type of processing. Based on this data, the CNC rack generates G commands for the tool path. This way you can program simple housing parts. To test the program, the machine operator starts the simulation mode on the CNC rack.
Problems
Here are the problems encountered when a program is written on a rack:
- Time. The machine does not work while the operator writes a program to process the part. Machine downtime means lost money. If the program contains more than 130 lines of code, then it is better to choose another programming method. Although, of course, it’s faster to write a program on a CNC machine than by hand.
- Marriage. The CNC machine does not compare the machining result to the 3D model of the part, so the CNC machine simulation does not show gouges or positive allowance. To debug the program, you need to lay down an extra workpiece.
- Not suitable for complex profile parts. It is not possible to program the processing of complex-profile parts on a CNC rack. Sometimes, for specific parts and standard sizes, manufacturers of CNC racks make special operations to order.
While the program is being created on the rack, the machine does not bring money to production.
In SprutCAM
SprutCAM is a CAM system. CAM is short for Computer-Aided Manufacturing. This is translated as “computer-assisted manufacturing.” A 3D model of a part or a 2D contour is loaded into SprutCAM, then the sequence for manufacturing the part is selected. SprutCAM calculates the trajectory of the cutting tool and displays it in G-codes for transmission to the machine. A post-processor is used to output the trajectory into G-code. The post processor translates internal SprutCAM commands into G-code commands for the CNC machine. It looks like
for translation from a foreign language.
The principle of operation in SprutCAM is presented in this video:
Advantages
Here are the advantages of working with SprutCAM:
- Fast. Reduces the time to create programs for CNC machines by 70%.
- Implementation without unnecessary workpieces. The program is checked before running on the machine.
- Rules out marriage. According to reviews from our users, SprutCAM reduces the occurrence of defects by 60%.
- Collision control. SprutCAM controls collisions with the part or working units of the machine, and incisions at rapid feed.
- Processing of complex-profile parts. In SprutCAM, for multi-axis operations, 13 strategies for moving the tool along the surface of the part and 9 strategies for controlling the tool axis are used. SprutCAM automatically controls the angle of inclination and calculates a safe processing path so that there is no collision of the holder or cutting tool with the workpiece.
Drawing up a control program for your CNC machine is possible in the full-featured version of SprutCAM. It needs to be downloaded and launched. After installation you will need to register. Immediately after registration, SprutCAM will start working.
For those who have just started trying, we provide a 30-day fully functional free version of the program!
SprutCAM has 15 configurations, including two special versions: SprutCAM Practitioner and SprutCAM Robot. To find out which configuration is suitable for your equipment and how much it costs, call 8-800-302-96-90 or write to info@site.
Information about the order of processing of the product on the machine is entered frame by frame. FRAME is a part of a control program, entered and processed as a whole and containing at least one command.
In each block, only that part of the program is recorded that changes in relation to the previous block.
A frame consists of words that define the purpose of the data that follows them.
For example:
N3 - frame sequence number
G02 - preparation function
(G01 - move in a straight line to the point
G02,G03 - circular interpolation clockwise or counterclockwise)
X - Coordinates of the end point of movement along the axes, Y - (for example, X+037540 (375.4mm)
Coordinates of the center of the arc during circular interpolation
F4 - feed code (for example, F0060 (60mm/min)) S2 - spindle speed code T2 - tool number
M2 - auxiliary function (tool change, table change, cooling switch on, workpiece clamping...).
L3 - enter and cancel correction of geometric information.
LF - end of frame.
To create a program for moving the working parts of the machine, you need to associate a certain coordinate system with it. The Z axis is selected parallel to the axis of the main spindle of the machine, the X axis is always horizontal. When compiling a program, they use the concept of zero, starting and fixed points.
Preparation of the control program includes:
1.Analysis of the part drawing and selection of the workpiece.
Selecting a machine based on its technological capabilities (dimensions, interpolation capabilities, number of tools, etc.).
Development of a technological process for manufacturing a part, selection of cutting tools and cutting modes.
4.Selection of the coordinate system of the part and the starting point for the tool.
5.Choice of the method of fastening the workpiece on the machine.
Placement of reference points, construction and calculation of tool movement.
Encoding information
Recording a program on software, editing and debugging.
The use of CNC machines has significantly aggravated the problem of using humans in production environments. Doing all
actions to manufacture a part with a machine in automatic mode left the person with the most difficult and uncreative work of installing and removing workpieces. Therefore, simultaneously with the development of CNC machine tools, work was carried out to create systems capable of replacing a person when performing specific actions that require the use of “MANUAL” labor.
Milling machine and multi-operation machine (machining center) with numerical control
3.3 Industrial robots
An industrial robot (IR) is a mechanical manipulator with program control.
A manipulator is a mechanical device that imitates or replaces the actions of human hands on a production object.
Industrial robots are divided into technological (variable)
properties of the object) and transport.
The technological robot performs welding, the transport robot moves the workpieces to the processing zone.
According to their carrying capacity they are divided into:
Object weight ultra-light up to 1 kg light 1 - 10 kg medium 10 -100 kg heavy 100-1000 kg super-heavy more than 1000 kg
Ultra-light robots assemble the device, while a heavy robot moves large workpieces.
PRs are also divided according to the number of degrees of freedom of the working body, according to the CNC system (closed and open, contour and positional, CNC, DNC, HNC).
Transport robot service area and workpiece movement path
Currently, transport robots are widely used to load technological equipment, deliver workpieces from the warehouse and transport parts to the warehouse. During stamping operations, transport robots feed blanks to the stamp and remove them.
Robots that weld car bodies and paint them are widely used. Robots are used in the assembly of electronic equipment, watches and other devices.
Together with technological equipment with CNC systems, industrial robots form the basis for comprehensive production automation.
Robots weld car bodies and install wooden panels on a machine for processing (examples of robot application)
Control questions:
1.Which CNC systems allow processing spherical surfaces on lathes?
2.Which CNC systems are advisable to use on drilling machines?
3.How many coordinates are interpolation possible when processing workpieces on lathes? - on milling machines?
4. How do cyclic program control systems differ from CNC systems?
5.What functions do industrial robots perform?
Sample test control card questions.
In what operations is it advisable to use CNC systems with contour control?
A). When turning stepped rollers.
B) . When milling double curvature surfaces.
IN). When machining holes in printed circuit boards.
What types of robots are used when painting complex-profile parts? A). Technological with contour control.
B). Large-sized with position control.
IN). Transport with contour control.
MINISTRY OF EDUCATION AND SCIENCE OF THE RF
MOSCOW STATE TECHNICAL UNIVERSITY MAMI Faculty: “Mechanical and Technological” Department: “Automated machine tools and tools” COURSE WORK by discipline Programmed processing on CNC and SAP machines Development of a control program for a numerically controlled machine Moscow 2011 Maintaining Technological preparation of the control program 1 Selection of technological equipment 2 Selecting a CNC system 3 Sketch of the workpiece, justification of the method for its production 4 Tool selection 5 Technological route for processing a part 6 Purpose of processing modes Mathematical preparation of the control program 1 Coding 2 Control program Conclusions from the work Bibliography coding machine part software control 2. Introduction
Currently, mechanical engineering has received widespread development. Its development is in the direction of significantly improving product quality, reducing processing time on new machines due to technical improvements. The current level of development of mechanical engineering places the following requirements on metal-cutting equipment: high level of automation; ensuring high productivity, accuracy and quality manufactured products; reliability of equipment operation; High mobility is currently due to the rapid replacement of production facilities. The first three requirements led to the need to create specialized and special automatic machines, and on their basis automatic lines, workshops, and factories. The fourth problem, most typical for pilot and small-scale production, is solved using CNC machines. The process of controlling a CNC machine is presented as a process of transferring and converting information from a drawing to a finished part. The main function of a person in this process is to convert the information contained in the drawing of a part into a control program understandable by the CNC, which will allow the machine to be controlled directly in such a way as to obtain a finished part that matches the drawing. This course project will examine the main stages of developing a control program: technological preparation of the program, and mathematical preparation. To do this, based on the drawing, the parts will be selected: workpiece, CNC system, technological equipment. 3. Technological preparation of the control program
3.1 Selection of process equipment
To process this part, we select a CNC lathe model 16K20F3T02. This machine is designed for turning parts of rotating bodies with stepped and curved profiles in one or several working strokes in a closed semi-automatic cycle. In addition, depending on the capabilities of the CNC device, various threads can be cut on the machine. The machine is used for processing parts from piece workpieces with clamping in a power-driven chuck and, if necessary, pressing with a center installed in the tailstock quill with mechanized movement of the quill. Technical characteristics of the machine: Parameter name Parameter value Largest diameter of the workpiece: above the bed above the support 400 mm 220 mm Diameter of the rod passing through the hole 50 mm Number of tools 6 Number of spindle speeds 12 Spindle speed limits 20-2500 min -1Limits of working feeds: longitudinal transverse 3-700 mm/min 3-500 mm/min Speed of fast strokes: longitudinal transverse 4800 mm/min 2400 mm/min Discretion of movements: longitudinal transverse 0.01 mm 0.005 mm 3.2 Selecting a CNC system
CNC device - part of the CNC system is designed to issue control actions by the executive body of the machine in accordance with the control program. Numerical program control (GOST 20523-80) of a machine - control of the processing of a workpiece on a machine according to a control program in which the data is specified in digital form. There are CNCs: -contour; -positional; positional-contour (combined); adaptive. With positional control (F2), the movement of the working parts of the machine occurs at specified points, and the movement path is not specified. Such systems allow processing only straight surfaces. With contour control (F3), the movement of the working parts of the machine occurs along a given path and at a given speed to obtain the required processing contour. Such systems provide work along complex contours, including curved ones. Combined CNC systems operate at control points (nodal points) and along complex trajectories. Adaptive CNC machine provides automatic adaptation of the workpiece processing process to changing processing conditions according to certain criteria. The part considered in this course work has a curved surface (fillet), therefore, the first CNC system will not be used here. The latest three CNC systems can be used. From an economic point of view, it is advisable in this case to use contour or combined CNC, because they are less expensive than others and at the same time provide the necessary processing accuracy. In this course project, the CNC system “Electronics NTs-31” was chosen, which has a modular structure, which allows you to increase the number of controlled coordinates and is intended mainly for controlling CNC lathes with feed servo drives and pulse feedback sensors. The device provides contour control with linear-circular interpolation. The control program can be entered either directly from the remote control (keyboard) or from an electronic memory cassette. 3.3 Sketch of the workpiece, justification of the method for its production
In this course work, we conditionally accept the type of production of the part in question as small-scale. Therefore, a rod with a diameter of 95 mm of simple rolled section (round profile) for general purpose made from steel 45 GOST 1050-74 with hardness HB = 207...215 was selected as a blank for the part. Simple sectional profiles for general purpose are used for the manufacture of smooth and stepped shafts, machine tools with a diameter of no more than 50 mm, bushings with a diameter of no more than 25 mm, levers, wedges, and flanges. During the blanking operation, the bushings are cut to a size of 155 mm, then on a milling and centering machine they are trimmed to a size of 145 mm, and here the center holes are simultaneously made. Since when installing a part in the centers, the design and technological base are combined, and the error in the axial direction is small, it can be neglected. A drawing of the workpiece after the milling-centring operation is presented in Figure 1. Figure 1 - workpiece drawing 3.4 Tool selection
Tool T1 To process the main surfaces of roughing and finishing, we select a right-hand cutter with mechanical fastening of a DNMG110408 plate made of GC1525 hard alloy and a clamp of increased rigidity (Fig. 2). Figure 2 - right through cutter K r b, mmf 1, mmh, mmh 1, mml 1, mml 3, mm γλ s Reference plate93 02025202012530,2-60-70DNMG110408 Tool T2 Figure 3 - prefabricated cutting tool l a , mma r , mmb, mmf 1, mmh, mmh 1, mml 1, mml 3, mmReference plate4102020,7202012527N151.2-400-30 Tool T3 To drill a given hole, select a GC1220 carbide drill for drilling for an M10 thread with a cylindrical shank (Fig. 4). Figure 4 - drill D c , mmdm m , mmD 21max, mml 2, mml 4, mml 6, mm91211.810228.444 Tool T4 To drill a given hole, select a GC1220 carbide drill with a cylindrical shank (Fig. 5). D c , mmdm m , mml 2, mml 4, mml 6, mm20201315079 Tool T5 For making internal thread M 10×1 select a tap GOST 3266-81 made of high-speed steel with helical grooves (Fig. 5). Figure 5 - tap 3.5 Processing route
The technological route for processing a part must contain the name and sequence of transitions, a list of surfaces processed during the transition and the number of the tool used. Operation 010
Procurement. Rental Cut the workpiece Ø 95 mm in size 155 mm, make center holes up to Ø 8 mm. Operation 020
Milling and centering. Mill the ends to size 145 mm. Operation 030
Lathe: Place the workpiece in the front drive and rear rotating centers. Installation A Transition 1 Tool T1 Pre-sharpen: · cone Ø 30 mm to Ø 40 · Ø 40 · cone Ø 40 mm to Ø 6 0 mm from length 60 mm to length 75 mm from the end of the workpiece · Ø 60 · Ø 60 mm to Ø 70 along an arc with a radius of 15 mm from a length of 85 mm from the end of the workpiece · Ø 70 · Ø 70 mm to Ø 80 mm at a length of 120 mm from the end of the workpiece · Ø 80 mm to Ø 90 · Ø 90 Leave a finishing allowance of 0.5 mm per side Transition 2 Tool T1 Finish sharpening according to transition 1: · cone Ø 30 mm to Ø 40 mm to a length of 30 mm from the end of the workpiece · Ø 40 mm from a length of 30 mm to a length of 30 mm from the end of the workpiece · cone Ø 40 mm to Ø 60 mm from a length of 60 mm to a length of 75 mm from the end of the workpiece · Ø 60 mm from length 75 mm to length 85 mm from the end of the workpiece · Ø 60 mm to Ø 70 along an arc with a radius of 15 mm from a length of 85 mm from the end of the workpiece · Ø 70 mm from a length of 100 mm to a length of 120 mm from the end of the workpiece · Ø 70 mm to Ø 80 mm at a length of 120 mm from the end of the workpiece · Ø 80 mm to Ø 90 mm along an arc with a radius of 15 mm from the length from the length of 120 mm from the end of the workpiece · Ø 90 mm from length 135 mm to length 145 mm from the end of the workpiece Transition 3 Tool T2 · Sharpen a rectangular groove 10 mm wide from a diameter of 40 to a diameter of 30 mm at a distance of 50 mm from the end of the workpiece. Installation B Transition 1 Tool T3 · Drill a hole Ø 9 40 mm deep. Transition 2 Tool T4 · Drill a hole with Ø 9 to Ø 20 to a depth of 15 mm. Transition 3 Tool T5 · Cut the thread with an M10 tap ×1 to a depth of 30 mm. Operation 040
Flushing room. Operation 050
Thermal. Operation 060
Grinding. Operation 070
Test. 3.6 Purpose of processing modes
Installation A Transition 1 - rough turning Tool T1 2.When pre-turning steel with a through cutter with a carbide plate, we select the depth of cut t = 2.5 mm. .When turning steel and depth of cut t = 2.5 mm, select feed S = 0.6 mm/rev. . .Cutting speed WITH v TO MV = 0.8 (, table 4 p. 263) TO PV = 0.8 (, table 5 p. 263) TO IV = 1 (Table 6 p. 263) 6.Spindle speed. 7.Cutting force. where: C R (, table 9 p. 264) 8.Cutting power. Transition 2 - finishing turning Tool T1 .Determination of the working stroke length L = 145 mm. 2.When pre-turning steel with a through cutter with a carbide insert, we select t = 0.5 mm for the depth of cut. .When turning steel and depth of cut t = 0.5 mm, select feed S = 0.3 mm/rev. .Tool life T = 60 min. .Cutting speed WITH v = 350, x = 0.15, y = 0.35, m = 0.2 (Table 17 p. 269) KMV = 0.8 (Table 4 p. 263) TO PV = 0.8 (, table 5 p. 263) TO IV = 1 (Table 6 p. 263) 6.Spindle speed. 7.Cutting force. where: C R = 300, x = 1, y = 0.75, n = -0.15 (Table 22 p. 273) (, table 9 p. 264) 8.Cutting power. Transition 3 - grooving Tool T2 .Determination of the working stroke length L = 10 mm. 2.When cutting grooves, the cutting depth is equal to the length of the cutter blade .When turning steel and depth of cut t = 4 mm, select feed S = 0.1 mm/rev. 4.Tool life T = 45 min.