Patent Application
20050055124
The present invention relates to the positioning probe and its control system that are used for detecting a dimension or position of a work piece and pausing motor movement.
Automation is a widely engaging aspect in the manufacturing industry. A lathe machine with computer numerical control is used in cutting a work piece. The work piece is mounted on a chuck and is attached to the rotational axis of a spindle. A cutting tool is inserted into a tool holder and secured on a turret. The turret carries the cutting tool to move in the Y-axis then forward in the X-axis to cut the work piece. In order to improve the cutting quality, to enhance efficiency and reduce set-up time, most lathe machine is furnished with a touch sensor or probe to perform the process.
In U.S. Pat. No. 4,879,847, refers to the designing of a probe to measure positions. The device retrieves the position information through a series mechanical action spring contact, balls and cylinders that react to a series of electrical connection. The mechanic design was complex and the production cost was expensive.
The object of the invention uses a more economical and efficient mechanics to build the positioning probe that equips on to the longitudinal axis of the machine. Further, it is an object of the invention to provide an accurate and efficient method to detect a position value for measuring a dimension or a position of a work piece when contact stage is occurred. Furthermore, it is an object of the invention to provide an accurate and efficient method to pause the motor movement when contact has occurred.
In one preferred embodiment of the invention the positioning probe is a cavity cylinder metal rod having multiple surfaces to allow different directions and angles of an electrically conducting object to make contact on the surface of the positioning probe. The object assembles with two cylinders to form metal rods that are a sensor head and a supporter. Sensor head means a cylindrical cavity that allows different angles of the tip of the cutting tool to contact sensor head surface. Cutting tool is an electrical conducting object which has a sharp edge at the tip of the front; the tip is the first portion to contact the sensor head or work piece. Supporter means two different diameters in a rod; the narrow side is a tail for holding, the wide side is connected to the media. Media means a non-conducting round nylon shape which is placed between the sensor head and the supporter to fasten together the different length screws. Two plugs are indented in the sensor head to connect the electrical conducting wire to the control system.
In a further embodiment of the invention the positioning probe utilize an optical signal to determine of contact positioning and motor control. Initially, the sensor head of the positioning probe has a given positive voltage from a power source. Other than the sensor head, all conducting components connected to the lathe machine are grounded to a zero voltage. When contact has taken place between the sensor head and the cutting tool, the voltage on sensor head is dropped to zero voltage. The signal is interrupted in the control system then the motor control is terminated its movement and the detected position value is stored in control center of the control system to be used. Detected position value means the last position signal received from the measuring device when sensor head and electrically conducting object is in contact.
Embodiments of the invention will now be described by way of examples only and with reference to the accompanying drawings wherein:
The preferred embodiment of the present invention will be described hereinafter in accordance with
Referring to the drawings
Referring to the drawing
The sensor head 301 has multiple surface diameters that are used to capably contact different directions and angles of the tip of the cutting tool 406. Referring to the drawing
Surface 311 for the cutting tool A, B, C and 1, 3 to measure X axis direction.
Surface 312 for the cutting tool 1, 2, 3 to measure Y axis direction.
Surface 313 for the cutting tool 2 to measure X axis direction.
Surface 314 for the cutting tool C to measure Y axis direction.
Surface 315 for the cutting tool B to measure Y axis direction.
Referring to the drawings
Lathe bed 402 has a pair of guide rods and a rack that are placed perpendicular in relation to the X axis of the lathe machine 401. The carriage table 404 perpendicularly saddles across the lathe bed. The motor 413 (show in
A linear scale 403 mounts parallel at the back of the guide rod of the lathe bed 402. The sensor head of the linear scale uses a bracket to mount on the carriage table 404 that is capable of moving in positions in X axis. Linear scale means the measuring device that can emit position signals through a sensor head along its rod. Position signal is an electrical pulse.
Referring to the
Referring to the drawing
An optical coupler 3206 includes a LED (light emitting diodes) and a light transistor. A circuit flows through the resistor 309 in serial from the power source 308 to the plug 307 that supplies a positive voltage to the sensor head 301. The current then passes through the resistor 310 that is connected in serial via the plug 306 to load the LED that generates a light signal. The light signal shines on the light transistor which then transmits an electrical signal to the control center 3201. This electrical signal means move-signal is stored in control center 3201 for MCU-move to detecting.
The MCU-move 3204 controls the motor 413 of its X axis movement and the MCU-move 3205 controls the motor 414 of its Y axis movement. For every movement, either the MCU-moves of 3204 or 3205 has to monitor difference kinds of signals and read the position value in the control center 3201 then compare the position value to a programmed target position X or Y for determinate the stage of movement. In particular, MCU-move 3204 will compare its value to the programmed target position of X; MCU-move 3205 will compare its value to the programmed target position of Y. The steps of the monitoring include:
(a) monitor the pass-by signal of the PC Computer 412, if is on, then go to the (b), otherwise check the move-signal is available or not. If yes, then go next, otherwise quit the proceeding;
(b) monitor the stop signal of PC Computer 412 is available. If not, then go to next, otherwise quit the proceeding;
(c) monitor the stop signal of the stop 411 is available. If not, then go to next, otherwise quit the proceeding;
(d) read position value of MCU-store 3202 or 3203 and compare to the programmed target position. If the value is difference then the motor is moved, otherwise the program ends.
Quit the proceeding means suspend the process, and then waits for the PC computer for further commands. End of program means the process of positioning detecting is complete but there was no contact between the positioning probe 300 and the cutting tool.
When the power on, as illustrated in the drawing
Herewith three stages are relative to the positioning detecting and motor control. The positioning probe 300 is held by the chuck 408 of the spindle 407. The circuit flows to the resistor 309 that is in serial with the power source 308 to the plug 307 for supplying the positive voltage to the sensor head 301. The power source's zero voltage is connected to the ground. In addition, the circuit through the plug 306 via the resistor 310 is in series connection with the optical coupler. Then the current loads the LED to illuminate the light transistor to produce an electrical signal that is transmitted to the control center 3201. This signal is retained in the control center 3201 as a flag for MCU-move monitoring. At this stage there is non-contact.
The turret with the tool holder 405 that is the cutting tool 406 inserted is carried by carriage table 405, which is driven by motors. The position signals emitted from the linear scales 403 of X axis to MCU-store 3202 and 410 of Y axis to MCU-store 3203 are stored in the control center 3201. Those signals store in the control center 3201 are represented of X and Y axis's position value and will be change and override from the movement of the carriage table 405 until detected position value occurs.
Once the tip of the cutting tool 406 is moved along on X and Y axis of the lathe machine, then in contact to the surface of sensor head 301. The sensor head 301 of the positioning probe 300 then short the voltage to ground. In other words, the voltage has changed to zero volts form the sensor head 301 of the positioning probe 300. At the result, the move-signal sent from optical coupler 3206 to the control center 3201 is terminated. In other words, the flag retain in control center 3201 is lose. This is the stage of means contact.
Thus, the signal emitted from optical coupler 3206 to the control center 3201 is interrupted. Either the MCU-moves 3204 or MCU-move 3205 cannot detect move-signal in the control center 3201 then abort all further processing means the motor movement is paused.
Meanwhile, the position value stored in the control center 3201 is by means of the detected position value when the contact stage is occurred. In particular, when the contact stage is occurred, any of linear scale is not emitted position signal for the carriage table 404 is not move. This is the stage of detected position value.
In another situation, the position probe 300 may be inserted to the cutting holder of the turret 405 for position detecting. The work piece holds on the chuck 408 of the spindle 407. The positioning probe 300 is inserted to the tool holder of the turret carry by the carriage table to forward to contact the work piece. The work piece is defined as an electrically conducting object. When the sensor head 301 of the positioning probe is in contact of the work piece, the sensor head 301 is shorts the voltage to ground. Then, the move-signal sent from optical coupler 3206 to the control center 3201 is terminated. In other words, the flag retain in control center 3201 is lose. This is the stage of means contact.
Thus, the signal emitted from optical coupler 3206 to the control center 3201 is interrupted. Either the MCU-moves 3204 or MCU-move 3205 cannot detect move-signal in the control center 3201 then abort all further processing that means the motor movement is paused.
Meanwhile, the position value stored in the control center 3201 is by means of the detected position value when the contact stage is occurred.
It should be apparent that the preceding description illustrates the current invention in one embodiment only and the invention is not restricted to the preferred embodiment. It should also be evident to those skilled in that art that variations and modifications to the preferred embodiment are possible without departing from the spirit and scope of the design. In particular, it should be understood that the invention can embody the sensor head 301 have multiple diameters on its axis a sensor head 301 of positioning probe 300 positioned in any direction and the number of different diameters on sensor head are not limited to the described preferred embodiment.
Further, it should be understood that the invention can embody the power source 308 to supply positive or negative voltage in direct current (DC) or positive voltage and negative voltage in alternating current (AC). When alternating current utilizes for supply power source to sensor head, one or more LED and capacity will be add to the circuit.
