Application of the hottest Pilz safety products in

2022-08-09
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Application of Pilz safety products in CNC machine tools

modern CNC machine tools are gradually developing in the direction of high speed, high efficiency, high precision, composite and other functions. In a high-speed and complex machine tool to ensure efficient production, safety and reliability is a necessary condition. Therefore, to evaluate the advantages and disadvantages of a machine tool, we not only need to see how powerful its functional units are: kPa, psi (lbs/in^2), kgf/cm^2, but also need to pay attention to how high its safety performance is. Improving the safety performance of CNC machine tools can not only reduce production accidents, protect personnel and machine safety, improve the added value of their own products, but also break through the technical barriers of western countries and increase export opportunities

as the largest free economic trade area in the world, the European Union has introduced a new method directive to eliminate technical barriers in order to establish a unified European market. These directives issued by the EU are highly targeted, systematic and easy to operate and implement. Therefore, they are also used by manufacturers in some countries and regions outside the EU. In addition to the reasons for putting products on the market, they also indicate the safety level of products and facilitate sales. Therefore, if you want to design a safe CNC machine tool, you can refer to the machinery directive 98/37/ec in the new method directive. In addition, the best way for manufacturers to make their products meet the basic requirements specified in the directive is to manufacture products according to standards, because these standards specify the technical measures to achieve the basic requirements specified in the directive. Some class C standards commonly used in the machine tool industry are as follows:

en 12415:2000 machine tool safety small CNC lathes and turning centers

en 12417:2001 machine tool safety machining centers

en 12478:2000 machine tool safety large CNC lathes and turning centers

en 1550:1997 safety requirements for the design and manufacture of chucks for clamping machine tool safety workpieces

en 12717:2001 machine tool safety drilling machines

en 12840:2001 machine tool safety Fully automatic or manual lathe without automatic control

en 13128:2001 machine tool safety milling machine (including boring and drilling)

according to the standard, the risk assessment and risk assessment of the machine will be required first. In the use of CNC machine tools, the rotation or linear movement of the shaft will cause friction and collision hazards to operators and maintenance personnel. Turrets and cutters of the magazine will also cause friction and cutting damage to operators and maintenance personnel. After risk assessment and evaluation, the safety level required by a CNC machine tool is usually above level 3

after identifying the hazards and risks of the machine, a series of measures must be taken to reduce the risks. The emergency stop button can be used to ensure that the machine can stop quickly in dangerous situations; Safety door protective devices, such as mechanical plug-in switches with or without locking, can be used to prevent personnel from entering the dangerous area at will and ensure that maintenance personnel can operate safely in the dangerous area; The safety monitoring speed function, debugging enable button and electronic handwheel can be used to monitor the overspeed and stop status of the machine, and ensure that personnel can safely debug the machine when the safety door is opened; The safety control module, such as safety relay or safety PLC, must be used to monitor the above safety functions to avoid the failure of the safety function caused by the failure of the control module itself

a small CNC machine tool is equipped with an emergency stop button, a mechanical safety switch with locking to monitor the inner safety door, and a mechanical safety switch without locking to monitor the outer safety door. After risk assessment and evaluation, the safety requirements for it are as follows: when any safety function is triggered, the power supply and corresponding enabling of the servo or frequency converter must be cut off, and the shaft stops running safely. For this application, according to the characteristics of less safety functions, we can choose a single safety relay as the safety control module. Here, we choose three PNOZ x2.8p safety relays and one s1sw P stop monitoring relay. The highest safety level of PNOZ x2.8p can reach level 4, which meets the application requirements; With 3 safety normally open output contacts and 1 normally closed auxiliary output contact. Each safety relay controls a safety function. K12 safety relay controls the mechanical safety switch with locking, as shown in Figure 1. The signal of its unlocking switch comes from the s1sw P stop monitor to ensure that the inner safety door can be opened only when the shaft stops running. K13 safety relay controls the mechanical safety switch without locking. K11 safety relay controls the emergency stop button and receives the safety signals transmitted by K12 and K13, as shown in Figure 3. This safety solution, with low cost, simple structure, clear wiring and convenient fault diagnosis, is suitable for the application of less than 4 safety functions

Figure 1

Figure 2

Figure 3

for a medium-sized and complex CNC machine tool, the following safety functions are usually available: main emergency stop button, tool magazine emergency stop button, tool magazine and work area safety door, debugging enable button, electronic handwheel, operation mode selection on and off, speed monitoring. After risk assessment and evaluation, the safety requirements for this machine tool are: press the emergency stop button, and the servo power supply and enable must be cut off; Open the safety door of the tool magazine, and the turret of the tool holder must stop running; When the safety door of the tool magazine is opened, the tool holder can be debugged through the enable button and jog button; Open the safety door in the working area, cut off the servo enable signal, and monitor the static state of the shaft at the same time; When the safety door in the working area is opened, the speed limit commissioning of the main shaft, x-axis, Y-axis and z-axis can be carried out through the combined operation of the enable button and the jog button or by using the electronic handwheel. At the same time, the speed monitoring module can be used to monitor the overspeed status of the rotating shaft or linear shaft. It can be found that this CNC machine tool has many safety functions, and there is a complex logical relationship between each safety function. If a single safety relay is used for control, it will lead to many problems, such as complex wiring, high cost, difficult fault diagnosis and so on. To this end, Pilz launched PNOZmulti modular safety relay, which can provide a cost-effective and perfect safety solution for this application

pnozmulti is a multifunctional and freely configurable modular security system. Unlike other PNOZ safety relays, PNOZmulti's safety circuit can be easily generated on a personal computer using a graphical configuration tool. PNOZmulti is composed of a PNOZ M0 (1/2) P basic module and several expansion modules. The basic module can be used alone, including 20 input points that can be connected to all safety functions such as emergency stop button, safety door, two hand controller, etc; Four 2A capacity semiconductor safety outputs; 2 relay safety outputs; One auxiliary non safety output and four test pulse outputs. The expansion module can be used to achieve the functions of increasing input and output points, speed monitoring and Fieldbus connection. Through the RS232 interface on the basic module, you can directly write programs to PNOZmulti, or use a card reader to write programs to SIM smart card and insert PNOZmulti to run

pnozmulti has the following characteristics:

1. Modular structure and flexible use

pnozmulti has three versions of basic modules, pnozm0p, pnozm1p and pnozm2p. Pnozm0p can not expand the input and output module, but can expand the communication module; Pnozm1p can expand input and output modules and communication modules; Pnozm2p is a basic module specially developed for press

2. Programmable, easy to understand operation, without special programming knowledge

pnozmulti adopts the graphic configuration tool PNOZmulti configurator to program with large oil output of oil inlet and return pipes, so as to achieve more configurations and less wiring. PNOZmulti configurator is available in many languages, including Chinese, German, English, Spanish, French, Italian and Japanese. With pnozmutli configurator, you can quickly complete a safe circuit by dragging and dropping with the mouse, shortening the design and development cycle. Each basic module needs to use a SIM card to store programs. There are two ways to download the program to the basic module. You can download the program to the SIM card through the card reader; The program can be downloaded to the basic module through the serial cable and the RS232 serial port on the basic module. The latest version of this configuration tool is 5.0.0

3. Powerful diagnosis function

fault diagnosis can be carried out in the following ways:

each input and output point is equipped with LED indicator light

dynamic program display function can be executed through serial cable and RS232 serial port on the basic module for fault diagnosis and equipment debugging

fault stack information can be used to quickly judge faults

diagnosis word can be used, Judge the status of each function block

can be used in conjunction with pmimicro diag, and then wait for a certain time for the human-machine interface according to the original speed to the original position to obtain visual diagnostic information

4. Safety speed monitoring can be carried out

pnozmulti can expand pnozms1p or pnozms2p, and reduce the diesel steam ratio for safety speed monitoring through incremental encoder or proximity switch, which can reach safety level 3 according to European standards. You can use pnozmsi1p Pnozmsi4p adapter is used to connect the drive of Siemens or haidenhain to obtain the signal of incremental encoder

5. Common standard functions can be controlled

pnozmulti can control common standard functions. Through pnozmi2p and pnozmc1p, common standard functions such as start button, reset button, or status signal output can be controlled; The communication of non safety status information can be carried out through common standard buses, such as PROFIBUS, DeviceNet, CANopen, CC link

therefore, using PNOZmulti can easily complete the safety function control of this medium-sized and complex CNC machine tool. Designers only need to connect the input and output to PNOZmulti respectively, and then use PNOZmulti configuator to complete the logical relationship between these inputs and outputs. In this way, not only the development cycle of designers is shortened, but also the cost is reduced

pilz's safety products are widely used in the machine tool industry. Whether foreign GILDEMEISTER, STAMA, Heller, or domestic well-known machine tool manufacturers such as Shenyang Machine Tool Group, Dalian machine tool, Shanghai heavy machine tool, Pilz can provide reasonable and cost-effective solutions according to customers' different requirements. (end)

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