Programming of CNC Machines. Ken Evans

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Programming of CNC Machines - Ken Evans

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active for manual positioning by any of the manual modes.

       4, 5, 6

      The 4, 5, and 6 buttons correspond with each of the rotary axes. When one is pressed, that axis becomes active for manual positioning by any of the manual modes.

       AXIS DIRECTION

      + and

      These buttons are used to select the manual feed axis direction. Pressing these buttons executes movement along the selected axis in the selected direction relative to the machine coordinate system—by Jog feed (or INC feed) or HANDLE—when the corresponding button is set to ON in the jog feed mode (or INC feed mode). The same is true for each of the linear and rotational axis buttons. As long as the button is held, the axis will move at a feed rate determined by the Feed Override dial or INC setting until released.

       Rapid

      After selecting the desired axis and pressing the Rapid button simultaneously with the + or – button, the machine will move along that axis at rapid traverse until released.

       Caution: Prior to activation, be sure the part, fixture, or clamping devices that are in the chosen path are not going to interfere. The axis will move at a rapid feed rate and a crash could occur!

      The Operator Panel in Figure 2-2 includes a Feed/Rapid % override dial you can use to control the rapid feed rate. This dial is used to reduce the rapid feed rate (G00). If it is positioned at 100, it corresponds to 100% of the rapid feed rate that the machine can generate. When override buttons are used, they are commonly incremented in steps of 10, 25, 50, and 100%.

       SPINDLE

      The spindle buttons are used exclusively during the machine’s manual operation for setup functions. The descriptions below explain their specific function:

       SPDL CW

      By pressing the SPDL CW button while in one of the operation modes REF, JOG, INC, or HANDLE, the spindle will start rotation in the clockwise (CW) direction. The spindle rev/min is adjusted by using the Spindle Override dial. When set at 100%, the spindle will rotate the last r/min commanded in the program. The spindle command is retained and will restart upon pressing the SPDL CW button. When the machine is first started, there has been no value established for the r/min. Therefore, if one of these buttons is pressed while in the modes listed above, an alarm will result. An r/min must be input via MDI or by activating the program. From that point on, as long as the machine is not turned off, the r/min will be activated at the last commanded value when one of these buttons is pressed.

       SPDL STOP

      Pressing the SPDL STOP button stops spindle motor rotation while in one of the operation modes listed above. However, pressing this button will NOT stop the spindle while in any of the Automatic execution modes.

       SPDL CCW

      Pressing the SPDL CCW button is exactly the same as pressing the SPDL CW except that the spindle will start rotation in the counterclockwise (CCW) direction.

       COOLANT

      Although not shown on this operator panel, there are buttons that control coolant flow during manual or automatic operation. In some cases, there is a manual switch to turn coolant on and off.

      The control panel described here is quite typical of the control panels used on CNC machines. The control panel switches and buttons may be distributed differently on the panel for each individual machine; however, the purpose and function of each switch and button remains the same. Some control panels are equipped with additional buttons or switches not shown here. Definitions and applications of these buttons or switches can be found in the manufacturer instruction manuals for the machines.

      The control panel is located at the front of the machine and is equipped with a CRT and with various buttons and switches, as illustrated in Figure 2-8.

      PC integrated controls are commonly identified with the lower case letter i after the controller series number, i.e., 0i. They allow you to use third party software like Excel, etc., and to connect to the Internet for diagnostic purposes and remote access. Modern machine tools are equipped with Ethernet connectivity to your company’s network (some offer wireless), thereby offering unlimited part program and tool file storage with easy access via Windows-based operating systems.

      For this controller, there is an access door on the upper left side of the display that contains a memory card slot and USB port. Some older controls still have a 3.5 floppy disk and possibly a PCMCI (Portable Computer Memory Card Interface) slot. All of these methods are used as a file storage medium and transfer.

      There are two alpha key arrangements. QWERTY (Figure 2-1) matches standard keyboards while the ONG style, which is more popular for 0i, is shown in Figure 2-8. A detailed description for the use of each button and its purpose on the control panel are presented in the following sections.

       POWER-ON AND POWER-OFF

      Located in the lower left hand corner of the control in Figure 2-8, the Power-On and Power-Off buttons are used to activate/deactivate the power to the control. Press these buttons to turn CNC power ON and OFF. The ON button is white in color and when it is ON, the key is lit. The OFF button is typically black in color and when the power is turned OFF to the control, the key is lit. At startup of the main power to the machine, the OFF button is lit. On older machines, these keys will be green and red in color respectively. Directly above these buttons are the Operation Selection buttons which are described in the same-named section of this chapter. Path Select is used for multi-path controls. For this controller, it is inactive.

image

       Note: The control is always turned ON after turning on the MAIN POWER switch, which is located on the door of the control system, typically at the back or side of the machine. The control is always turned OFF before the MAIN POWER switch is turned OFF.

       CRT Display

      The CRT is the display screen on which all the program characters and data are shown. Sizes vary from around 9 inches to approximately 15 inches. Displays are color, monochrome, or liquid crystal displays (LCD). FANUC displays (shown here) offer 8.4, 10.4, and 15-inch screens.

       Reset

      Pressing the RESET button resets or cancels an alarm; it can also be used to cancel an automatic operation. An alarm can only be cancelled if its cause has been eliminated.

      When the reset button is pressed during automatic operation, all program-commanded axis feeds and spindle revolutions are cancelled. The program will return to its

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