Center adjustment of CNC lathes. Mach3 is a program for controlling CNC machines. Features of setting up CNC lathes

Mach3 is a CNC control program that allows you to automate the processing of workpieces. The use of CNC machines is relevant for large enterprises and small workshops. The difference lies only in the characteristics and dimensions of the machines that are used in certain situations. Consider the issue of using Mach3 at the initial stages of its development.

• A modern milling machine equipped with a CNC module allows it to interact with a conventional personal computer or laptop;
• By installing the Mach3 driver on your PC, you can develop control programs;
• After development, the program is loaded into the memory of the CNC module;
• The task of the computer is to set up all the necessary parameters for the operation of the CNC;
• In addition to process automation, through a PC, you can manually control the movements of the cutting tools of the machine, control their movements relative to the workpiece or desktop;
• The work of Mach3 is based on the following scheme: computer - master - milling equipment. To carry out such management, you will need the appropriate program;
• Mach3 is a great example of modern software that controls and configures machines;
• Mach3 is designed to work with all Microsoft operating systems;
• The program works like a normal "window" type application;
• Mak3 differs in wide functionality, intuitively clear interface;
• At the same time, beginners, for whom CNC setup is something completely new, should carefully study the instruction manual. It takes a minimum of time to adapt to working with CNC through a special program. This is due to a well-designed interface and a clear control principle.

Preparing to work with Mach3

Photo Mach3 - programs for controlling the CNC machine

Numerical control, that is, CNC, is an advanced development in the field of building machine tools. The program simplifies management, automates all processes. Competent CNC tuning using a program via a PC allows you to minimize the human factor and reduce the likelihood of errors to zero.

At the same time, it is important to understand that if the setting is done incorrectly, you can break the cutters, incorrectly process the workpiece, disable the CNC module and other equipment components.

To avoid such mistakes and unpleasant incidents, you should start with competent preparation for the operation of CNC machines.

1. Complete the machine connection. You must make sure that the machine is prepared for work, receives high-quality power from the mains. For many machines, special programs are available that allow you to check the condition of the equipment, the health of its individual components via a PC.
2. Install Mach3 on your personal computer or laptop. Please make sure that your PC meets the minimum system requirements. Mach3 is not a "heavy" program, because almost any computer can easily "pull" it.
3. The program may require Russification in some cases. The licensed version is in English, but special russifiers are widely available online. It is not recommended to use pirated programs like Mach3, since such software can contain serious errors that can disable your machine, even if the setup was done correctly. The license costs about 12 thousand rubles.
4. Try to optimize the operation of the operating system by disabling all kinds of pop-up windows, unused programs. Nothing should interfere with you while working with the machine.
5. Do not run third-party programs in parallel with Mach3. This is especially true for computer games, watching movies and other content that requires impressive resources from the PC. Otherwise, the setting may be incorrect, which will affect the quality of processing and the machine itself.
6. If in parallel you want to create control programs for a CNC machine, or use a computer not only to work with Mac3, then divide the hard drive into subsections. For CNC software, install a separate operating system. The logical partition of the hard disk must be fully dedicated to machine control. This will allow not to occupy the entire PC with CNC control issues. Use this operating system specifically for hardware settings, do not download third-party software there, minimize the set of programs.

Working with the program

When the preparation steps are over, you will need to proceed with the direct setup of the Mac3 program.

1. Carefully study all the buttons that are available in the Mack3 menu. Many are afraid of their huge number. But the presence of the Russified version will allow you to quickly understand everything.
2. Depending on the type of machine, you need to open the corresponding tabs. For milling equipment, you will need tabs for parameters of electric motors, part speeds, parameters for ports, spindle, etc.
3. By purchasing the licensed version of the software, you will find all descriptions of the settings in the user manual. Or you can find it on the World Wide Web.
4. If you conditionally correctly performed the settings for the machine through the Mac3 program, with commands given from the keyboard, the electric motors of the equipment will begin to rotate and move. It is important that the portal moves smoothly, neatly and freely. This indicates that the setting is correct.
5. Run a run. This is the name of the trial manual movement of tools. The corresponding button for the run is in the Mac3 program.
6. The run is defined by the corresponding icon that allows you to turn this trial mode on and off.
7. Pay attention to the jog ball. When running, it should be highlighted. It is used to control the tools of the machine with the mouse. The closer the cursor is to the jog wheel when clicked, the higher the rotation speed of the electric motors will be. In addition to the mouse, you can use the keys on the keyboard to activate the tool.
8. Control of tool movements can be step-by-step and continuous. In the case of continuous, the machine tool moves continuously while you hold down the corresponding key or mouse button. The step-by-step mode assumes that after pressing the button, the portal will move to a strictly specified distance. You can set the step size yourself.

Mach3 is offered to customers with a detailed instruction manual. Based on the official manual, you can adapt the program to a particular machine. Operate strictly according to factory instructions. Only they make it possible to perform a competent setting of the parameters of the CNC equipment. If the setting is correct, the compiled control program will automate the machine, adapt it to perform certain operations with workpieces.

))) This is a very long story about the machine set with its back .... I already got it all in this way .... But there is an approach to the button, I already checked it.

I create UE in Artkam Pro 9
Machine control program WinPC-NC

What happened on it was posted on the photo, set up by phone with specialists from CNC Mashine, through them the machine was bought. But they don’t approach this with particular reverence, they took their brains out for a long time, they seemed to make it work, and now I’m mastering everything on my own, there’s a lot of information already, my head is boiling, and a lot of things I don’t understand ...
For example, I cut everything according to the standard, and I cut it right away with a finishing engraver, that is, I don’t change any speeds and so on, I only adjust the feed rate in the control program, as I understand it, it changes the speed of the spindle along the axes. I do about 60% and cut ... Now I'm studying those documentation for the program, but the translation leaves much to be desired, it's like listening to Chinese radio ...

In stock!
Protection against radiation during welding and cutting. Big choice.
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The CNC type CNC system is characterized by the following operating modes.

Information input mode. input of a control program (CP) or initial data for it from an external carrier manually or via a communication channel; information analysis; error output to display devices; placement of UE in the system memory.

Auto mode: processing of a part according to UE; automatic feed control; accelerated development of UE; accumulation of operational information (counting the number of parts, registration of processing time, etc.).

Operator Intervention Mode into the process of automatic control: execution of the technological shutdown operation, skipping of UE frames and their processing without issuing control commands, as well as correction of technological modes, tool codes and satellite codes.

Manual mode: machine setting and manual movement control; debugging UE; development of tool movements when setting the movement speed manually; recruitment and development of the UE frame, its memorization and storage; formation of UE from individual frames, visualization of frames, input of corrections of various types, diagnosing the mechanisms of a machine tool, tool, CNC system, etc.

Edit Mode: search for the desired frame of the UE and its output to the display device, correction of frames, their replacement, insertion and deletion.

Information output mode UE to external devices - a puncher, a printing device, a compact cassette, to external memory, as well as to a high-end computer or to a local area network.

Calculation mode the required values ​​by formulas (for example, cutting mode parameters and geometric transformations), the formation of UE based on input information, etc.

Display mode when the selection and visualization of information, dialogue, etc.

Diagnostic Mode, during which emergency and diagnostic warnings are automatically generated.

When adjusting the program of the machine, the operator uses the appropriate modes, introducing the adjustments necessary for processing.

Features of setting up CNC machines are determined by the control system, since the mechanical, hydraulic, pneumatic and electrical systems are the same as those of similar machines with traditional control systems.

The specificity of setting up CNC machines lies in the fact that during operation it is necessary to periodically (when switching to the processing of a new workpiece) to adjust the necessary characteristics of hydraulic, pneumatic, mechanical assemblies, electrical devices, electronic devices, CNC units, automatic adjustment systems, adjustable feed drives .

Programmable function keys are located on the operating console of the operator or on the machine panel. The modern programming languages ​​used provide the operator with an interactive mode. When working, the operator uses the possibility of programming at the workplace and visualization on the screen of the CNC system of the trajectories of movement of the working bodies in the given and current coordinates in a form convenient for the operator and technologist. In accordance with the technological map, the operator sets the technological parameters of processing (cutting speed, feed, etc. .).

The adjustment of the simplest elements is performed by the worker-operator. He uses a map that contains the initial data for setting up tools (their length and overhang) and fixtures. If during processing it is required to ensure the 8th (or more) quality of accuracy, the adjustment for processing the first workpiece is carried out by the method of test passes.

In the process of adjusting electronic and electrical devices of control systems for CNC machine tools, the adjuster conducts oscillography of voltage and waveforms, as well as transients. It performs adjustment of the CNC sequentially for each device, block, node (for example, readout, input devices, arithmetic device, indication, interpolation, memory blocks, speed reference node, etc.). Without changing the scheme of the node, block, device, the optimal values ​​of the output signals are obtained, ensuring the accuracy and performance of the device as a whole. Adjustment is performed using tuning elements provided in the design, block diagram, node, device (for example, using a variable resistor), or by selecting any of the circuit elements that affect the output parameter.

In the CNC, the implementation of adjustment work is associated with a variety of measurements carried out at control points, the results of which evaluate the output parameters of the node, block and device as a whole. CNC setup is considered completed after checking the functioning of the CNC machine in various modes and in accordance with the specified program.

The worker-operator checks the functioning of the CNC machine after adjustment in three stages.

1. Checking the program without tools, fixtures and workpieces. With the help of manual control, the machine nodes are set to their original position, and then automatic control is turned on according to the program. Control the movement of all nodes and their return to their original position. Control is carried out on limbs with the help of stops, indicators, etc.

2. Processing a mock-up workpiece, made in some cases from sheet metal, plastic, etc. Usually, such an operation is performed if the workpieces are complex and their number is limited.

3. Processing of the control (reference) part. A comprehensive verification of the accuracy of processing on a CNC machine is the verification of a reference part (standard), machined according to UE. On fig. 9.21, and shows a drawing of a standard for comprehensive testing of the quality of setting up a multi-purpose CNC machine. For machines with a horizontal spindle, the standard can be made in the form of a square. For horizontal machines with a ratio of maximum movements along the X and Z axes more than 1:6 and for vertical machines with the same ratio of maximum movements along the X and Y axes, it is recommended to use two standards. The standard is finally processed on the base surfaces with an accuracy twice as high as the tolerances for the surfaces being checked.

In addition to a comprehensive check, it is necessary to check the accuracy of the center distances of the machined holes. To do this, according to the program in the standard, five holes are drilled and bored according to the H7 grade. The length of the holes must be greater than or equal to the diameter. It is possible to bore holes to check the center distances and on the standard for a comprehensive check. The check is carried out using a microscope or a device designed to measure center distances.

For horizontal machines, the deviation from the alignment of the holes processed with the rotation of the table is checked. The measurement is performed twice, taking each of the bored holes as the base. The deviation from the alignment of the tested axes is equal to the largest of the obtained deviations.

On fig. 9.21, b shows the standard for a CNC lathe. The part is processed in compliance with the technical parameters (cutting mode, material, cutting tool geometry, coolant) recommended by the equipment manufacturer.

On CNC machines, tests are carried out for maximum loads and cutting conditions are specified for characteristic types of processing and tools. When testing for the maximum force of the drive of the main movement and feed drives, drilling with a tool of the largest diameter and milling with end mills are carried out.

Features of setting up CNC lathes

At the beginning of the shift, the basic functions of the movement of the machine are checked. In order to thermally stabilize the machine and the CNC device, the spindle is rotated at medium speed at idle and the CNC device is powered for 20 ... 25 minutes (while the machine is warming up).

According to the setup map, a cutting tool and equipment for fixing the workpiece are selected. Check the condition of the instrument. Install the tool in the corresponding positions of the turret support indicated in the setup chart.

Adjust the cams that limit the movement of the caliper and its zero (initial) position. The UE is entered from the CNC control panel from a form or from an external memory cassette. The UE is checked first in frame-by-frame mode, and then in automatic mode, observing the correctness of its implementation.

Fix the workpiece in accordance with the setup chart. Perform dimensional adjustment of the cutting tool. Process the workpiece according to UE. They determine the dimensions of the finished part and enter the necessary corrections from the CNC control panel (when processing a batch of blanks, they periodically check the dimensions of the parts and, if necessary, introduce corrections).

When processing the first workpiece, it is necessary to observe the cutting process (especially chip formation and roughness of the machined surface); if necessary, you should enter corrections for cutting conditions (from the CNC control panel).

Features of setting up multi-purpose CNC machines. Mounting the jig

It can be performed directly on the machine table or on a satellite fixture (PS).

Base elements are installed on the PS, orienting the workpiece relative to them. The location of the base and fasteners must correspond to the setup chart, since installation errors depend on this. If for the first time a workpiece processing program is worked out on the machine from several sides, then it is necessary to determine the coordinates of the table center from absolute zero along the X axis. This coordinate for this machine is a constant value and can be used when setting up bases for other setups. The position of the PS, and hence the workpiece, is predetermined by the technologist (programmer), who develops the program in absolute (relative to machine zero) or relative coordinates, taking into account the position of the workpiece zero relative to machine zero. (Machine zero is the initial position of the machine table and spindle at which all encoders indicate zero.)

The base surfaces of the workpiece and the support surfaces of the PS on which it is installed form a coordinate system, the beginning of which is called the zero of the workpiece (Fig. 9.22, a). If you set the position of the workpiece in relation to the machine coordinate system with dimensions X "and Y", then during processing (for example, holes 1) in the program, movement along the X and Y axes, etc. can be specified. Movement along the X0, Y0, Z0 axes can be obtained due to the zero offset device available on the machine, by typing the coordinate values ​​on the control panel when setting up the machine for this operation.

Sometimes the basing of the PS 4 hull is carried out using the base bars B 1 and B 2 (Fig. 9.22, b). These strips form the coordinate system of the PS, the position of which in relation to the coordinate system of the given machine is known and can be taken into account when compiling the program.

In some cases (Fig. 9.22, c), the base elements are installed parallel to the movements of the table in coordinates, calibrated with an indicator, fixed (in the general case, in such a place on the table where it is most convenient to place the workpiece), and then find the position of the coordinate system of the workpiece with respect to to machine zero. To do this, insert a mandrel with a diameter d into the spindle (Fig. 9.22, d) and move the table to a position in which the mandrel touches the base bars B 1 and B 2. The indication panel displays the values ​​of the coordinates, which are then used to control the zero offset.

It is possible to arrange the installation elements with base bars B 1, B 2, B 3 along the grooves of the table, which is in the zero position of the machine, and measure the distances X (to the measuring mandrel) and Z (to the base end surface of the spindle). These distances (taking into account the diameter of the mandrel) are taken into account when shifting the zero of the machine (see Fig. 9.22, c).

After installing the PS, it is necessary to enter the base coordinates, which is carried out by aligning the spindle axis with the base surface or the axis of the workpiece. At the same time, the distance from the base elements to absolute zeros is fixed in all coordinates. To enter the base coordinates, an auxiliary tool is used, which is installed in the machine spindle, and end measures. If the basing is carried out along the hole, then the base coordinates are entered using a center finder installed in the spindle using a mandrel. After alignment of the spindle axis with the axis of the hole, the base coordinates are entered by floating zero correctors.

Installing cutting and auxiliary tools in the magazine

Measurements of lengths and diameters for which the tool is set are carried out outside the machine. The operator enters this data into the corrector of the CNC system.

Additional tuning of some tools is performed, if necessary, directly on the machine based on the results of control measurements of the machined surfaces. Changing some dimensions of the processed surfaces is possible by introducing a correction on the control panel. The easiest way is to correct the machining length along the Z coordinate. Often, the correction is entered on the radius of the cutter when working in the circular interpolation mode (for example, when machining holes, a curved outer contour, and in other cases).

The placement of tools in the nests of the magazine, turret, etc. is performed in accordance with the program map. In this case, it is necessary to carefully check the number of the tool (arbor) with the number of the magazine socket, and on machines where the tool number is coded, set the appropriate code combination on the shank of the mandrel.

When installing in a magazine, special attention must be paid to a tool working with an initially oriented spindle, since it must be installed in a cell in a certain way. In addition, it is necessary to check: tool sharpening; fastening drilling chucks on the cone of the mandrel and drills in the chuck; fastening of end mills in adapter bushings; fixing the tool in collet chucks; setting threading chucks and fixing the tap in the adapter sleeve; fastening of mounted drills and reamers on floating mandrels; runout of drills and taps when installed in cartridges in order to reduce it.

If there is no tool setting device outside the machine, the length of the tool is determined on the machine. Depending on the value of the Z coordinate, the length of the tool is measured from the end of the spindle to the top of the cutting edge, or the deviation of the actual length of the tool from the programmed one is determined.

When machining with coolant, it is necessary to check the condition of the protective elements of the machine, the absence of gaps between the protection elements, the operation of the pump and the presence of coolant in the system.

A comprehensive check of the quality of setup on a CNC machine is the manufacture of a suitable part according to UP, the quality of which is evaluated by a measuring laboratory.

During normal use of the CNC machine, if the workpiece is re-machined, it is necessary to skip the test program at least once a week. In the event of a defective part, when working according to the NC, a test program is also introduced, which allows you to establish errors in the preparation of the program, a malfunction of the CNC, unsatisfactory operation of the feed drives, a violation of the sequence of technological commands and other defects in the operation of the machine.

By evaluating the results of running the test program, a malfunction in a circuit, block or group of blocks is determined with the participation of an adjuster or technologist. Further actions are typical for a specific design of the CNC and are indicated in the technical documentation.

MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION

FEDERAL AGENCY FOR EDUCATION

St. Petersburg Institute of Mechanical Engineering (LMZ-VTUZ)

A.M. Aleksandrov

SETUP AND OPERATION OF CNC MACHINES

Tutorial

Recommended by the Educational and Methodological Association for Education in the Field of Mechanical Engineering Automation (UMO AM) as a teaching aid for students of higher educational institutions studying in the following areas: "Design and technological support of machine-building industries", "Automated technologies and production" and in the specialties "Mechanical engineering", "Metal-cutting machines and complexes", "Automation of technological processes and productions in mechanical engineering

St. Petersburg

UDC 621.9.06 - 52

A.M.Aleksandrov Adjustment and operation with CNC: Tutorial. - St. Petersburg: PIMash Publishing House, 2009. - 124 p.

The training manual deals with the issues of setting up and operating CNC machines, including machine control in various modes, technological adjustment and dimensional adjustment, as well as automation of control of the processing process.

The manual is intended for students of technological specialties, as well as for specialists in the field of operation of CNC machines.

Ill. - 69, bibl. - 35 names.

Reviewers: Doctor of Technical Sciences, prof. V.V. Maksarov (NWTU) Ph.D., Assoc. R.N. Bityukov (PIMAsh)

© St. Petersburg Institute of Mechanical Engineering 2009

INTRODUCTION

Adjustment of CNC machines is the final stage of the technological preparation of automated production, which sums up all the previous work on the design of the technological operation and the compilation of control programs.

For successful commissioning and efficient operation of a CNC machine, the adjuster requires high qualifications in various fields of technology. The adjuster must perfectly know the design of his machine and be able to control it in all modes. He should be well versed in technological equipment - fixtures, cutting and auxiliary tools. When introducing new programs, the adjuster often finds himself in the role of a technologist-programmer, and in the process of daily operation of the machine, he performs the functions of a specialist in electronics and mechanics.

Without exaggeration, we can say that in modern production, the CNC machine tool adjuster is one of the central figures. This is a generalist (preferably with a higher education) with deep knowledge and practical skills in mechanical engineering technology, programming, electronics and computer technology. In the profession of an adjuster, one cannot do without such qualities as creative activity and the ability to work independently with technical literature. This is required by the original nature of the tasks being solved, as well as the constant improvement of CNC machines and various auxiliary devices.

The role of the adjuster in the operation of the FMS is especially important, where, in addition to setting up the machines themselves, it is necessary to ensure a clear interaction of all production modules, including transport and loading devices and automatic control tools.

The tutorial does not claim to be a complete description of the entire range of tasks related to the adjustment of automated equipment. The presentation of the material is limited to the adjustment of CNC machines as separate technological modules. In Sections 1 and 2, the issues of technological adjustment and dimensional adjustment are considered. Section 3 reflects the features of automated control of the processing process.

1. CNC MACHINE SETUP

1.1. Basic setup steps

The ESTD standards (GOST 3.1109-82, etc.) establish two terms: adjustment and adjustment.

Adjustment - preparation of technological equipment and technological equipment for the implementation of a technological operation.

Adjustment - additional adjustment of technological equipment and (or) technological equipment when performing a technological operation in order to restore the values ​​of parameters achieved during adjustment.

With regard to CNC machines, setup includes preparing fixtures and tools, moving the working bodies of the machine to a fixed position, setting program zero offsets and tool offsets, trial processing of the first part, correcting errors and shortcomings in the control program. Adjustment consists mainly in the timely introduction of corrections to the tool (due to dimensional wear or replacement of a dull tool). This assumes that the CNC machine is in good condition and does not require "electronic" adjustment, which is performed by representatives of the relevant engineering services or service organizations.

In the technological adjustment of a CNC machine, the following main stages can be distinguished:

- exit to a fixed position;

- installation of fixtures and tools;

- dimensional setting;

- input of the control program;

- trial processing;

- evaluation of the program and its adjustment (for the new PM).

The most important stage is the dimensional setting, which consists in coordinating the coordinate systems of the machine, program and tool. The dimensional tuning technique requires a more detailed study and is discussed in detail in Section 2.

For an approximate estimate of the time spent on setting up CNC machines, you can use simplified formulas (Table 1.1), which establish the connection between the preparatory and final time of the TPZ (min) with the number of tools in the setup K (pcs) and the duration of the automatic cycle tC (min). When setting up robotic technological complexes (RTC) or flexible production modules (FPM), it is recommended to increase the normative values ​​of TPZ by 5%.

Table 1.1 Formulas for calculating the preparatory-final time

for setting up CNC machines

1.2. Exit to a fixed position

Among the basic (characteristic) points of the CNC machine, it is necessary to highlight the fixed position (FP) and the zero of the machine*.

The fixed position is the reference point of the measuring system and is determined by special devices (travel stops, limit switches, position sensors, etc.), which are rigidly fixed on the machine guides. As a rule, AF sensors are installed at the stroke limit for each coordinate.

The machine zero corresponds to the origin of the machine coordinate system. Ultimately, all programmed movements are converted to the machine tool system and are worked out by servo drives from the machine zero.

For some machines, the FP and machine zero are the same, which is the reason for the confusion of these concepts in many manuals. However, in the general case, the FP and the zero of the machine differ from each other and must be considered separately (Fig. 1.1).

Fig.1.1. Examples of the relative position of the zero of the machine and the FP:

a - for a lathe; b - for a milling machine

* Depending on the design of the machine, to the base points from -

they also wear a tool change position, a table change position -

satellites, control position, etc.

For example, for lathes (Fig. 1.1, a), the zero of the machine M is combined with the axis of rotation of the spindle (Z axis), and the FP is located at the travel limit along the X coordinate. For milling machines (Fig. 1.1, b), it may be convenient to take zero machine M in the center position of the table, which does not coincide with the FP in two coordinates X and Y. Relationship between machine zero

and FP is set in the form of machine parameters X FP , YFP , ZFP, the values ​​​​of which are recorded in the energy-protected memory of the machine. adjustment

and FP sensors are fixed at the factory. Additional adjustment of the sensors during daily operation is allowed only in case of emergency. Usually limited to changing the values ​​of parameters X FP , YFP , ZFP , with which you can position the zero of the machine at any point in the workspace.

After turning on the machine and the CNC, the adjuster must bring the working bodies into the FP for each coordinate. This is necessary to bind the machine coordinate system to the measuring system of the machine. The exit command to the FP is set in manual mode by pressing special buttons on the control panel. Usually, each coordinate has its own exit button in the FP. In some CNC models, to enter the FP, you need to specify not only the coordinate, but also the direction of movement ("+" or "-"). The automatic selection of the sequence and direction of the exit to the FP is also applied. In this case, only one button is provided on the remote control, regardless of the number of coordinates. The output of the working bodies in the FP for each coordinate is confirmed by a light indication or a special message on the display screen. In most modern CNCs, it is possible to enter the FP not only in manual, but also in automatic mode using a special G-command.

The movement of the working bodies in the FP is carried out, as a rule, at high speed with braking when approaching the exact stop sensor. In addition, the machine is equipped with warning and emergency sensors.

stop. One of the options for the constructive implementation of these stops is shown in Fig. 1.2. A ruler 5 with grooves is fixed on the guides of the machine, and a block of limit switches 4 is fixed on the movable body. Emergency cams I and 7, warning cams 2 and 6, and an exact stop cam 3 are installed in the grooves of the ruler.

Fig.1.2. Ruler with traveling cams and block of limit switches

The action of cam 3 on the corresponding limit switch gives the command to slow down the travel speed (prepare for exact stop). The stop itself comes from the zero mark signal of the feedback sensor. Between two adjacent zero mark signals there is a gap of 2 to 10 mm of travel, depending on the type of sensor. In this regard, it is not indifferent at what moment, in relation to the exact stop signal, the limit switch from cam 3 will actuate to slow down the speed.

On fig. 1.3. shows a graph of the speed V of the working element from its path S, explaining the various stopping conditions depending on the interval between the braking command and the exact stop signal.

Fig.1.3. Graph of change in the speed of movement of the working body when reaching a fixed position

At the beginning of the movement in section OA, the speed increases to the specified value V. Exact stop on the signal of the feedback sensor must be carried out at point C. The standard conditions for braking and exact stop will be met if the command to slow down occurs at point B.

In case of premature issuance of a braking command at point B1, the working body will move for a long time at low speed and may stop at point B1 instead of point B (due to the unstable and jerky nature of movement at low speeds).

If the deceleration command is late (at point B2), despite the sharp braking, the working body will run over point B and only after reversing movement at point B2 will it reach the set point B. In this case, due to the fuzzy operation of the limit switch, the reverse may not occur. The working body will go further at a slow speed until the next zero mark signal in a row.

This situation is unacceptable, since the location of the FP (and hence the zero) of the machine becomes uncertain. The working body stops either in one or the other FP, the distance between which is equal to the step between the signals of the zero mark. To get out of this uncertainty should be due to a small displacement of the exact stop cam along the groove of the ruler.

At the boundaries of the working stroke of the working body, emergency stops are provided that protect the nuts of the lead screws from colliding with the supports, rolling screw pairs from scattering balls, tables and calipers from leaving the guides, etc. But the operation of the limit switch from cams I or 7 (see Fig. 1.2) is already an emergency in itself, since the machine has two types of preventive stops: from cams 2 and 6 or by limiting the working area using the settings. In some cases, it is necessary to change the position of the preventive stops, for example, when changing the chuck or moving the tailstock for lathes. At the same time, the position of the exact stop cam should not be changed, especially if the machine has lead screw error compensation.

1.3. Installing fixture and tools

When installing fixtures and tools, the adjuster is guided by the following list of technological documents:

- setup chart (KN/P);

- operating card (OK);

- sketch map (KZ);

- information coding card (CCI).

The main documents here are the setup chart and sketch cards that illustrate the setup process. It should be noted that the standard form KN/P (GOST 3.1404-86) is not quite suitable for modern CNC machines, the setup of which is characterized by an increased level

Many novice furniture makers are faced with the need to create facades based on MDF boards. Moreover, the requirements for products in a highly competitive environment are quite high.

Products must be of high quality, meet modern standards and trends, in addition to having a stable flow of customers, the entrepreneur must fulfill their orders as quickly as possible. It is possible to do work efficiently and quickly only if technological devices are used for work. In this case, it is CNC machines. What they are and how they work, we will tell below.

What does this abbreviation mean?

The definition of this concept is as follows: Computer numerical control. That is, a machine running on numerical control is capable of performing certain actions that are given to it using a special program. The operating parameters of the machine are set by means of numbers and mathematical formulas, after which it performs work according to the requirements specified by the program. The program can set parameters such as:

• power;
• work speed;
• acceleration;
• rotation and more.

Features of CNC machines

The technique of creating furniture parts on a modern device of this type includes several stages of work:

All mechanical actions that the equipment performs are the embodiment of the sequence that is written in the control program.

Modern CNC machines are complex electromechanical devices and require skilled use. The main operation of the machine is carried out by two people:

• adjuster;
• CNC machine operator.

The installer is entrusted with a more complex array of work, he performs the adjustment and readjustment of the device, and the operator must monitor the workflow and carry out easy adjustment.

Actions of the adjuster and operator of the CNC machine

Stages of work of the adjuster look like this:

• selection of a cutting tool according to the map, checking its integrity and sharpening;
• selection according to the setup map of the specified dimensions;
• installation of the cutting tool and clamping chuck, checking the reliability of fastening the workpiece;
• setting the switch to the position "From the machine";
• checking the working system at idle;
• the introduction of punched tape, which is carried out after checking the tape drive mechanism;
• verification of the correctness of the specified program for the CNC control panel and machine and the light signaling system;
• fixing the workpiece in the chuck and setting the switch to the "According to the program" mode;
• processing of the first workpiece;
• measuring the finished part, making adjustments to special switches-correctors;
• processing of the part in the "According to the program" mode for the second time;
• taking measurements;
• transfer of the mode switch to the "Automatic" position.

This completes the setup process and the operator of the CNC machine starts to work. He must do the following:

• change oils;
• clean the work area;
• lubricate cartridges;
• check the machine for pneumatics and hydraulics;
• check the exact parameters of the equipment.

Before starting work, the operator of the CNC machine must check its operation using a special test program, he must also make sure that lubricating fluid is supplied and that oil is present in the hydraulic system and limit stops.

In addition, he must check how secure the fastening of all appliances and tools, as well as how the furniture blank corresponds to the specified technological process of the machine. Followed by take measurements for possible deviations from the accuracy of zero adjustment on the instrument and other parameters.

And only after these manipulations can you turn on the CNC machine itself:

• the workpiece is installed and fixed;
• then the program of work is introduced;
• punched tape and magnetic tape are loaded into the reader;
• press "Start";
• after the first part is processed, it is measured for compliance with the previously specified model.

Areas of application of CNC machines

CNC machines are used in various service and manufacturing industries:

• for processing wood and wood boards;
• for plastic processing;
• stones;
• complex metal products, including jewelry.

CNC devices have a number of such functions., how:

• milling;
• drilling;
• engraving;
• cut;
• laser cutting.

Some models of CNC machines have the ability to combine different types of material processing at the same time, then they are called CNC-based machining centers.

Advantages of CNC machines

The use of CNC-based machine tools and machining centers in the production makes it possible to complete such work on time, which would be impossible without their use. For example, when producing furniture facades from MDF in this way, you can perform complex relief decors which is simply impossible to do manually. So, thanks to special graphic design programs, you can implement the most daring design decisions.

In addition, mass production of MDF facades using large-format CNC machines is possible without the need for pre-cutting the boards and allows you to do a full cycle of their processing, which greatly saves time and labor.

The price of CNC-based equipment is such that you need to think carefully before buying it whether it will cost-effective specifically for your production facilities. If you have a stable flow of customers, and they are willing to pay for original design solutions, then you can safely invest in such equipment.

A feature of CNC-based machines is their reliability and the possibility of trouble-free operation for many years. But when working with them, you must follow all safety rules, as well as select only qualified operators and adjusters. Poor quality work of personnel can disable the device ahead of schedule.