JPS62114808A - Floating type rotary tool - Google Patents

Abstract

PURPOSE:To avoid getting an unmachineable state to cutting load in deburring, by installing a servomotor, a rotary tool body, a pulse oscillating device, etc., in a tool holding head of a machine, while installing a controller, a servoamplifier, etc., in the others. CONSTITUTION:A bracket 1, a servomotor 2, a shaft 3 performing an axial stroke, a rotary tool body 4 and a pulse oscillating device 5 are all attached to a tool holding head of a machine M. Likewise,a pulse counter 6, a controller 7 independent from a controller Mc of the machine M, and a servoamplifier 8 controlling the servomotor 2 are installed in the others. And, the controller 7 detects size of machining load in comparison with the reference value, and outputs a floating control signal, which makes a rotary cutter 4a approach or keep away to or from a work W according to this machining load, to the servoamplifier 8. With this constitution, heavy and light cutting operations are repeated and smooth machining is performable.

Description

Detailed Description of the Invention [Technical Field] The present invention is attached to a tool mounting head of an industrial robot, a special processing machine, or a machining center, and is suitable for edge removal, cutting, or grinding. Relating to a floating rotary tool with force safety features.

<Prior art> A grinder or a rotary cutter (including the above claim, hereinafter referred to as a rotary cutter) is installed on the tool mounting head of an industrial robot, special processing machine, or machining center (hereinafter referred to as the machine, including the above claims). When performing deburring, cutting, or grinding (hereinafter referred to as machining, including the above claims) with a rotary cutter installed, cutting becomes impossible due to an increase in the cutting load on the rotary cutter. In order to avoid such situations, various safety devices have been developed. For example, such safety devices include those that allow the tool to detach from the robot arm if excessive cutting reaction force is applied to the rotary cutter, and those that support the rotary cutter so that it can be retracted from the workpiece and prevent excessive cutting reaction force from being applied to it. Some robots have a configuration in which when the robot arm and tool move backward by more than a certain value, a touch sensor detects this and stops the movement and rotation of the robot arm and tool based on a detection signal.

Deburring robots often cut excessively, and it is difficult to predict deburring, making it difficult to implement safety devices.

For example, the "R Grinder Robot Arm Mechanism" disclosed in Japanese Patent Application Laid-Open No. 60-94294 is a safety device for deburring robots, and it is undeniable that the rotation of the grinding wheel will stop if the deburring becomes large. ``Control method J for polishing robots, etc.'' in Japanese Patent Application Laid-Open No. 59-187438 is not intended for deburring.

1 Grinding robot 3 disclosed in Japanese Patent Application Laid-Open No. 59-187485 reads the travel path of the grinding wheel using a roller contact type stroke sensor installed in front of the grinding wheel so that it operates with a slight time delay. Since they are separated from each other, the machine follows the shape of the workpiece only when the surface to be ground is flat, and it is suitable for grinding the machined surface as well as for removing relatively small particles by machining. It is not suitable for a paring robot that scrapes off large particles. 1 Patent Patent Application No. 59-214509 "Robotic device for deburring" utilizes the fact that when a rotary tool encounters a large deburr and cuts excessively, the air motor rotates at a low speed and the pressure in the compressed air pipe increases. This is detected by a pressure sensor and input as a stop signal to the robot controller. Therefore, although the robot arm is distorted, serious situations such as damage to the tool or workpiece can be avoided. In other words, when a single-turn tool encounters a large burr and becomes unable to cut, at the stage of heavy cutting,
This is no more than a safety device to stop the robot. ``Positioning mechanism for automatic grinding device'' disclosed in Japanese Utility Model Application No. 60-109849 is equipped with a position error correcting device having a gauge section, and is not of the type that requires safety JA for deburring.

On the other hand, one worth noting is JP-A-60-2085.
There is a deburring method using an automatic deburring device in No. 8. This uses a grinder that is supported by a spring as an end effect, and the grinder compresses the spring with grinding pressure so that it moves away from the workpiece. The above displacement of the grinder is eliminated by constantly detecting the displacement and manually inputting it to the controller of the industrial robot to give a movement equal to the above displacement to one or two required robot arms, and as a result, the grinder is adjusted to the appropriate position. A smooth machined surface is obtained by floating along the machined surface while maintaining the grinding pressure, and then grinding the corner in a fixed dimension from the outer edge of the corner. The spring needs to be quite thick in order to hold it stably, and the spring shrinks only a small amount in response to changes in grinding pressure. Since the grinding wheel is traced, the sensing cannot be said to be very sensitive, so if it suddenly encounters a large grindstone, it is undeniable that the rotation of the whetstone will stop temporarily or fall into extremely slow rotation.On the contrary, if the grindstone is very uneven, This method has the drawback that vibrations are detected, making it difficult to move the robot arm appropriately.

In addition, since this method constantly changes the robot arm's teaching path according to the grinding pressure, general-purpose software that moves the robot arm along the teaching path cannot be used, and new advanced general-purpose software is required, making the system expensive. There is a drawback. Furthermore, it has the disadvantage that it cannot be applied to industrial robots of different manufacturers or models, or other specialized machines or machining centers.

Other noteworthy works include JP-A-59-232
There is a grinding speed control device for a grinder in a machining center in No. 748, but this requires software for the machining center controller that connects the controller to the machining center controller and constantly captures and processes the controller's signals. Also, it is impossible to process uneven surfaces and edges that cannot be taught.

Conventionally, a touch sensor, vision sensor, or laser sensor has been used to detect the position of a workpiece when a rotary cutter is attached to a machine and processed.

The cost of vision sensors and laser sensors is expensive, accounting for several 10% of the total system cost.

In addition, the grinder was subject to significant wear, and accurate position detection was not possible unless the touch sensor and vision sensor position detection was modified to account for the amount of wear on the grinder.

<Objective of the Invention> The present invention was devised in view of the above-mentioned points, and the tool itself has a floating function to avoid an unworkable state due to the cutting load during cutting and grinding such as deburring. In addition, the present invention provides a floating rotary tool that is equipped with safety features that can prevent damage to 4i1 machines and seals during breakage, and that can be applied to machines of different manufacturers and models by simply installing them.

<Structure of the Invention> As shown in FIGS. 1 and 2, the floating rotary tool T of the present invention comprises a bracket (l) which can be freely attached to the tool mounting head of a machine (the figure shows an industrial robot) M. , a servo motor 2 attached to the bracket 1, a shaft 3 attached to the bracket 1 and stroked in the axial direction by the servo motor 2, and a rotary tool main body 4 connected to the shaft 3;
A pulse oscillation means 5 that oscillates pulses according to the rotational speed of the rotary cutter 48 of the rotary tool body 4, a pulse counter 6 that inputs and counts the signal of the pulse oscillation means 5, and is independent of the controller Mc of the machine M. and a servo amplifier 8 that controls the servo motor 2 using control signals from the controller 7.

The controller 7 inputs the count signal and compares it with a single or multiple reference values to detect the magnitude of the machining load, and controls the rotary cutter according to the machining load to maintain an appropriate machining state. When one loaf of 48 was attached to the workpiece W, a floating control signal (to rotate the servo motor 2 in the forward or reverse direction) was output to the servo amplifier 8. ing. That is,
As shown in FIG. 3, the controller 7 inputs the count signal and compares it with a single basic 1s value corresponding to the appropriate processing load.
When it is large, a control signal is output to the servo amplifier 8 to move the one-turn cutter 4a closer to the workpiece W (to rotate the servo motor 2 in the forward direction), and when it is small, the one-turn cutter 4a is moved further away from the workpiece W. Is the control signal outputted to the servo amplifier 8 (which causes the servo motor 2 to rotate in the reverse direction), or is the count signal compared with two reference values, large and small, as shown in Figure 4, and processed? When it is greater than or equal to the reference value (large) corresponding to the load (small), outputs a control signal to the servo amplifier 8 to bring the rotary cutter 4a closer to the workpiece W (rotates the servo motor in the required direction); Also, when it is smaller than or equal to the reference value (small) corresponding to the processing load (large), a control signal is sent to the servo amplifier 8 to move the rotary cutter 4a further away from the workpiece W (rotate the servo motor in the opposite direction). It is designed to be output as follows.

The rotary tool main body 4 includes a rotary cutter 4a and a cutter rotation motor 4b.

The cutter rotation motor 4b is optimally an air motor, but may also be an electric motor or a hydraulic motor.The pulse oscillation means 5 includes a gear that is attached to a shaft and rotates, and teeth of the gear intersect in close proximity to the gear. It is best to configure the switch with a proximity switch that oscillates a pulse every time, since it is resistant to vibration and does not oscillate erroneous pulses.

<Example> FIG. 5 is an overall configuration diagram of a floating rotary tool according to an example of the present invention. In this embodiment, an electromagnetic contactor 9 is interposed between a servo amplifier 8 and a servo motor 2. The controller 7 of this embodiment is constructed as shown in the flowchart of FIG. However, when the rotary cutter 4a is rotated without contacting the workpiece W (that is, when there is no load), the rotary cutter 4a reaches its maximum rotation, and the count signal from the pulse counter 6 also reaches its maximum. The stroke of the shaft 3 moves downward and reaches its mechanical limit, and if left as it is, there is a risk that the servo motor 2 will seize up. For this reason, shaft 3
A lower limit detection limit switch 10 for detecting the lower stroke limit of The servo motor 2 is configured to stop rotating. At this time, the controller 7 selectively processes the count signal from the pulse counter 6 and rotatably controls the servo motor 2 to stroke the shaft 3 upward. Furthermore, when the count signal from the pulse counter 6 is smaller than the reference value, the stroke of the shaft 3 moves upward and reaches its mechanical limit, so an upper limit detection limit switch 12 is provided to detect the upper limit of the stroke of the shaft 3. When the striker 11 strikes the switch piece, the signal is input to the controller 7, and the controller 7 turns off the electromagnetic contactor 9 and stops the rotation of the servo motor 2. . At this time as well, the controller 7 selectively processes the count signal from the pulse counter 6 to control the servo motor 2 to rotate so as to stroke the shaft 3 downward.

FIG. 6 is a flowchart showing an example of the controller 7.

Initially, the controller 7 causes the rotary cutter 4a to stand by at the upper limit position. That is, when the rotary cutter 4a is not in contact with the workpiece W and is under no load, the count signal maintains the maximum value, so a control signal is sent to the servo amplifier 8 to reversely rotate the servo motor 2 so that the shaft 3 strokes to the upper limit. and input the detection signal of the upper limit detection limit switch 12 to the electromagnetic contactor 9.
is turned off, the servo motor 2 stops rotating, and the rotary cutter 4a is initially placed on standby at the L limit position.

When a start signal for rotating the rotary cutter 4a is input, the brake of the servo motor 2 is released, and then a control signal to bring the rotary cutter 4a closer to the workpiece W is output to the servo amplifier 8, and the timer is turned on. Then, a start signal is sent to the controller Mc of the machine M so that the rotary cutter 4a waits until it descends slightly above the intermediate level between the upper limit position and the lower limit position, and the rotary cutter 4d approaches the workpiece W for the first time when the timer is up. It is designed to output . When the rotary cutter 4a comes into contact with the workpiece W, the input count signal changes.

The count signal is compared with a single reference value corresponding to an appropriate machining load, and if the count signal is large, a control signal is sent to the servo to bring the cutter 4a closer to the workpiece W (to rotate the servo motor 2 in the forward direction). A control signal is outputted to the amplifier 8, and when it is small, a control signal is sent to the servo amplifier 8 to move the rotating cuffer 4a further away from the workpiece W (to rotate the servo motor 2 in the reverse direction).
It is designed to output to. Therefore, it is possible to obtain a smooth machined surface by repeating single-layer cutting and light cutting finely, and by repeatedly grinding to a certain dimension from the outer edge of the burrs, etc., it is possible to eliminate burrs, irregular uneven surfaces, and other surfaces that cannot be taught. It is possible to process various surfaces and edges.

On the other hand, if the rotary cutter 4a does not touch the workpiece, the controller 7 inputs the detection signal of the lower limit detection limit switch IO when the shaft 3 strokes to the lower limit, turns off the electromagnetic contactor 9, and turns off the servo. The rotation of the motor 2 is stopped and a work stop signal is output to the controller Mc. Furthermore, when a start signal is input to rotate the rotary cutter 4a again after the worker has made adjustments, the brake of the servo motor 2 is released, and then a control signal is issued to bring the rotary car, the cutter 4a, closer to the workpiece W. While outputting to the servo amplifier 8, the timer is turned on to wait until the one-rotation cutter 4a rises slightly above the intermediate level between the upper limit position and the lower limit position, and the rotary cutter 4a approaches the workpiece W for the first time when the timer is up. Thus, a start signal is output to the controller Mc of the machine M.

Note that the circuit may be configured so that the electromagnetic contactor 9 is directly opened and closed without inputting the detection signal of the limit switch 10.12 to the controller 7.

<Effects of the Invention> As explained above, the floating rotary tool of the present invention has a servo motor attached to a bracket that can be attached to a tool mounting head of a machine, and a one-turn cutter attached to a shaft stroked by the servo motor. It supports the rotary tool body including the motor for rotating the cutter, generates pulses corresponding to the number of rotations of the rotary cutter using a pulse oscillation means, counts these pulses with a pulse counter, and controls the machining load using a controller independent of the machine controller. A floating signal that moves the rotary tool away from the workpiece if the rotational speed corresponding to a large processing load is small, and moves the rotary tool closer to the workpiece if the rotational speed corresponding to a small processing load is large. is configured to be input to the servo amplifier of the servo motor mentioned above, so it is possible to obtain a smooth machined surface by repeating heavy cutting and light cutting finely, and it is possible to repeatedly grind to a fixed dimension from the outer edge of the paris etc. This makes it possible to process edges, irregularly uneven surfaces, and other surfaces and edges that cannot be taught, and is also equipped with safety features that can avoid breakage, damage, or distortion of machines such as industrial robots, tools, or workpieces. Since the controller is completely independent of the machine's controller and roller, it can be applied to machines of different manufacturers and models by simply installing it.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the entire system including the floating rotary tool of the present invention. FIG. 2 is an enlarged view of the main mechanical parts of the floating rotary tool of the present invention in a configuration different from that in FIG. 1. FIG. 3 is a flowchart of one example for explaining the operation of the controller constituting the floating rotary tool of the present invention, and FIG. 4 is a flowchart of another example. FIG. 5 is a conceptual diagram of the entire system including a floating rotary tool according to an embodiment of the present invention. FIG. 6 is a flowchart according to an example for explaining the operation of the controller constituting the floating rotary tool according to the above embodiment. T... Floating rotary tool, M... Machine Mc ・1 controller, W 1111 m workpiece, l... bracket. 2. Servo motor, 31. Shaft, 4. Rotating tool body, 4a. Rotating cutter, 4b. Cutter rotation motor, 5.1. Pulse oscillation means, 6. Pulse counter, 7-... Le J Goki, 8... Servo amplifier,

Claims (3)

[Claims] (1) A bracket that can be freely attached to the tool mounting head of a machine, a servo motor attached to the bracket, a shaft that is attached to the bracket and stroked in the axial direction by the servo motor, and a shaft that is connected to the shaft. a rotary tool body, a pulse oscillation means that oscillates pulses according to the rotation speed of a rotary cutter of the rotary tool body, a pulse counter that inputs and counts signals from the pulse oscillation means, a controller, and the control device. and a servo amplifier that controls the servo motor using a control signal from the controller. A floating type rotary tool that outputs a floating control signal to the servo amplifier to move the rotary cutter closer to or farther away from the workpiece. (2) The above controller inputs the count signal and compares it with a single reference value. If the count signal is large, it outputs a control signal to the servo amplifier to move the rotary cutter closer to the workpiece, and if it is small, it outputs a control signal to the servo amplifier to bring the rotary cutter closer to the workpiece. The floating rotary tool according to claim 1, wherein the floating rotary tool outputs a control signal to a servo amplifier to move the rotary cutter away from the workpiece. (3) The controller compares the count signal with two reference values, large and small, and outputs a control signal to the servo amplifier to bring the rotary cutter closer to the workpiece when it is greater than or equal to the reference value (large), Further, when the cutter is smaller than or equal to the reference value (smaller), a control signal is output to the servo amplifier to move the rotary cutter further away from the workpiece. floating rotating tool.