JP2005219089A6 - Electric servo press - Google Patents

Abstract

An object of the present invention is to prevent the occurrence of an accident in advance by reliably monitoring the runaway of a servo motor.
A linear scale 33 for detecting an absolute position of a slide, an encoder 39 for detecting an absolute angle of a main gear or a main shaft in a power transmission mechanism, a pulse signal is output in accordance with the rotation of a servo motor 21, and A pulse coder 40 that detects a pulse signal, and an NC device 42 that monitors each signal from the linear scale 33, the encoder 39, and the pulse coder 40, or a mutual shift amount of each calculated value calculated from each signal are provided.
[Selection] Figure 3

Description

  The present invention particularly relates to an electric servo press of a hand-in die that performs a pressing operation manually.

  An electric servo press converts the rotational driving force of a servo motor into a vertical reciprocating motion of a slide through a power conversion mechanism such as a ball screw, an eccentric mechanism (crank mechanism or eccentric mechanism), a link mechanism, etc. It is comprised so that a workpiece | work may be pressed between. This electric servo press has the excellent advantage of being able to control the slide so that it can have any slide motion that matches the processing conditions of the workpiece, and can perform high-precision forming and improve productivity. Therefore, in recent years, it is becoming popular as an alternative to conventional press machines using clutch brakes.

  In a drive system of a conventional press machine, a flywheel is rotated by a main motor and rotational energy is stored in the flywheel. The stored rotational energy is transmitted to the main gear via a clutch brake device, and the slide is moved up and down. It is made to move. In this case, in the so-called hand-in die in which the operator manually loads the workpiece into the mold and unloads the processed product for each shot of the press, the safety one-stroke mode is used, and the slide is dead. When the press work is performed near the point and a press stop signal is input at a position rotated by a predetermined crank angle from the bottom dead center, the clutch of the clutch brake device is turned off and the brake is turned on, so that the flywheel Rotational power from is mechanically cut off and the slide is stopped near top dead center. When the slide is stopped, work such as taking in and out of the material is performed (see Patent Document 1).

JP 7-290296 A

  By the way, the above-mentioned electric servo press employs a mechanism in which the rotational energy for rotating the main gear is directly transmitted from the servo motor via the timing belt, and cuts off the energy source like a conventional press machine. Since there is no clutch brake device to be used, the rotational power of the servo motor is transmitted to the slide even when the top dead center is stopped. For this reason, for example, if the mechanism that detects the position of the slide incorrectly recognizes the actual slide position due to disconnection, failure, disturbance, etc., and the position control is performed, the slide position is shifted due to an incorrect command signal from the controller. End up. Therefore, in the automatic press where the human body does not enter the mold during the press operation by the protective fence, an interlock sensor is provided on the door or window, and the servo motor power supply is shut off and mechanical by the signal from this sensor. The brake is applied.

  However, when the servo press is used with the hand-in die in the safe one-stroke mode, the operator thinks that the press stops at the top dead center, and puts the hand into the press die during the ascent process of the slide. Since the product is taken out, if the servomotor runs away, the conventional overrun detection (detection that the slide has exceeded the top dead center) will not cause an accident due to the unexpected lowering of the slide. Can not prevent. In addition, in the method of detecting a deviation error between the command value and the actual movement amount used in the conventional servo control at a certain setting level, since the deviation at the start and stop is large, the above-described accident is also prevented in advance. It is insufficient as a method.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electric servo press that can reliably monitor the runaway of a servo motor and prevent an accident from occurring. Is.

In order to achieve the above object, an electric servo press according to the first invention
In the electric servo press that processes the workpiece by converting the rotational driving force of the servo motor into the vertical reciprocating motion of the slide via the power transmission mechanism,
From position detection means for detecting the absolute position of the slide, angle detection means for detecting the absolute angle of the main gear or main shaft in the power transmission mechanism, signals from the position detection means and angle detection means, or from the signals It is characterized by comprising monitoring means for monitoring the amount of deviation of each calculated value calculated.

The electric servo press according to the second invention is
In the electric servo press that processes the workpiece by converting the rotational driving force of the servo motor into the vertical reciprocating motion of the slide via the power transmission mechanism,
Position detecting means for detecting the absolute position of the slide, angle detecting means for detecting the absolute angle of the main gear or main shaft in the power transmission mechanism, and a pulse for detecting a pulse signal output in accordance with the rotation of the servo motor And a monitoring means for monitoring each signal from the position detecting means, the angle detecting means, and the pulse detecting means or the mutual shift amount of each calculated value calculated from the signals. is there.

  In the first invention, the absolute position of the slide is detected by the detection signal from the position detection means, and the slide position is detected based on the detection signal from the angle detection means for detecting the absolute angle of the main gear or the main shaft. Therefore, for example, when the position detection means for detecting the absolute position of the slide is broken or disconnected, and the detected value indicating the current position of the slide is different from the actual one, or the current die height value in the controller When the main gear and main shaft rotate unexpectedly and unnaturally when the actual value is suddenly replaced with another value, the abnormal state can be detected promptly, thereby generating an accident. Can be prevented in advance.

  Also, if the slide position is differentiated with respect to time, the slide speed can be obtained, and if the absolute angle of the main shaft is differentiated with respect to time, the angular speed of the main shaft can be obtained. Is stored in a data table or the like, it is possible to detect an abnormal state from these slide speeds or main shaft angular velocities.

  In the second aspect of the invention, in addition to the detection signals from the position detection means and the angle detection means, the slide position is based on a detection signal from a pulse detection means for detecting a pulse signal output in accordance with the rotation of the servo motor. Therefore, the abnormality detection of the press can be more reliably performed by the triple detection means.

  Next, specific embodiments of the electric servo press according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a side partial sectional view of an electric servo press according to an embodiment of the present invention, and FIG. 2 shows a rear partial sectional view of the electric servo press. The electric servo press 1 according to the present embodiment relates to an example applied to a so-called hand-in die in which an operator manually loads a workpiece into a die under a slide and unloads a product after processing. is there.

  In this embodiment, the electric servo press 1 includes a main body frame 2, a slide 3 that is supported on a substantially central portion of the main body frame 2 so as to be movable up and down, and a bolster that is mounted on the bed 4 so as to face the slide 3. 5 is provided. An upper die (not shown) is attached to the lower surface of the slide 3, and a lower die (not shown) is attached to the upper surface of the bolster 5, and the workpiece is press-formed between the upper die and the lower die. . In the hole formed in the upper part of the slide 3, the main body of the screw shaft 7 for adjusting the die height is inserted so as to be rotatable around its axis while being prevented from coming off. Further, the screw portion 7 a of the screw shaft 7 is exposed upward from the slide 3, and is screwed into a female screw portion below the plunger 11 disposed above the screw shaft 7.

  A worm wheel 8 a of a worm gear 8 is mounted on the outer periphery of the main body of the screw shaft 7, and a worm 8 b of the worm gear 8 screwed into the worm wheel 8 a is output from an induction motor 9 mounted on the back surface of the slide 3. The shaft is connected via a gear 9a. The induction motor 9 is configured to be flat and compact by reducing the axial length.

  The upper portion of the plunger 11 is rotatably connected to the lower end portion of the first link 12a via the pin 11a, while the upper end portion of the second link 12b is rotatably connected to the main body frame 2. Between the upper end portion of the first link 12a and the lower end portion of the second link 12b, two connecting holes provided on one side of the triaxial link 13 are rotatably connected via pins 14a and 14b, respectively. ing. Further, the connection hole on the other side of the triaxial link 13 is rotatably connected to the eccentric shaft 28 of the slide drive unit 20. Thus, the first link 12a, the second link 12b, and the triaxial link 13 constitute a toggle link mechanism.

  A servo motor 21 for driving the slide 3 is attached to the side of the main body frame 2 with its axis oriented in the left-right direction of the press, and its axis is directed above the servo motor 21 in the left-right direction of the press. An intermediate shaft 24 is rotatably arranged, and a timing belt 23 is wound between a first pulley 22a attached to the output shaft of the servo motor 21 and a second pulley 22b attached to the intermediate shaft 24. Yes. A drive shaft 27 is rotatably supported above the intermediate shaft 24, and a gear 26 provided on one end side of the drive shaft 27 is engaged with a gear 25 attached to the intermediate shaft 24. The eccentric shaft 28 is provided at the central portion in the axial direction of the drive shaft 27, and the other side of the triaxial link 13 is rotatably connected to the eccentric position of the outer peripheral portion of the eccentric shaft 28. Yes.

  An oil chamber 6 sealed between the lower end surface portion of the screw shaft 7 is formed in the slide 3, and the oil chamber 6 passes through an oil passage 6 a formed in the slide 3, It is connected to a switching valve 16 that switches between supplying and discharging the operating oil into the oil chamber 6. The operating oil supplied into the oil chamber 6 through the switching valve 16 is sealed in the oil chamber 6 at the time of press processing, and the pressing force at the time of pressurization is transmitted to the slide 3 through the oil in the oil chamber 6. It is supposed to be. When an overload is applied to the slide 3 and the hydraulic pressure in the oil chamber 6 exceeds a predetermined value, the oil is returned into the tank through a relief valve (not shown), the slide 3 is cushioned by a predetermined amount, and the slide 3 and the mold Is not to be damaged.

  In addition, a pair of brackets 31 and 31 project from the two upper and lower portions toward the side surface of the main body frame 2 on the back surface of the slide 3, and a position detection rod 32 is attached between the brackets 31 and 31. It has been. The position detection rod 32 is provided with a scale portion for position detection, and a main body portion of a linear scale (position sensor) 33 is inserted so as to freely move up and down. The linear scale 33 is fixed to an auxiliary frame 34 provided on the side surface of the main body frame 2. Here, the auxiliary frame 34 is formed in a vertically long shape in the vertical direction, the lower end portion is attached to the side surface portion of the main body frame 2 by a bolt 35, and the upper portion is formed by a bolt 36 inserted in a long hole in the vertical direction not shown. It is supported so as to be slidable in the vertical direction, and the side portion is in contact with and supported by a pair of front and rear support members 37.

  As described above, the auxiliary frame 34 is structured such that only the lower side (which may be the upper side) is fixed to the main body frame 2 and the upper side is supported so as to be movable up and down. It is not affected by expansion and contraction. Thereby, the linear scale 33 can accurately detect the slide position and the die height without being affected by the expansion and contraction due to the temperature change of the main body frame 2.

  As described above, the position of the slide 3 is detected by the linear scale 33 as a position detector for detecting the absolute position of the slide 3, and the encoder for detecting the absolute angle of the main gear 38 attached to the drive shaft 27. (Angle detector) 39. Here, the encoder 39 is attached to the press body via a vibration isolator. In this case, in order to make it difficult for noise to enter the output signal of the encoder 39 due to vibrations, a special coupling is used that is hard against displacement in the rotational direction and has a somewhat soft characteristic against misalignment between the axes.

  In the control block diagram of the electric servo press of this embodiment shown in FIG. 3, when the operator operates the start switch 41, a slide start signal is input to the NC device (controller) 42. The NC device 42 includes a central processing unit (CPU) 42a for executing required arithmetic processing, an input circuit 42b, a storage circuit 42c, an output circuit 42d, a feedback circuit (FB circuit) 42e, etc. When the activation signal is input through the input circuit 42b, a speed command (voltage command for commanding rotation of the servo motor 21) and a servo ON command (servo motor 21 command) are set based on the slide motion data preset in the memory circuit 42c. A command for enabling control) is output from the output circuit 42d to the servo amplifier 43. The servo amplifier 43 converts the power supplied from the power supply power supply 44 into a drive power signal corresponding to the speed command and outputs the drive power signal to the servomotor 21. The servo amplifier 43 is fed back with a pulse signal from a pulse coder 40 built in the servo motor 21, and the servo amplifier 43 has a small deviation between the motor rotational speed calculated from the pulse signal and the speed command. The servo motor 21 is controlled so that

  On the other hand, a feedback signal from the linear scale 33 that detects the absolute position of the slide 3 is input via a feedback circuit 42 e in the NC device 42. Based on this feedback signal, the NC device 42 positions the slide 3 at a target position calculated from the slide motion data.

  Further, an angle detection signal of the main gear 38 from the encoder 39 that detects the absolute angle of the main gear 38 is input via a feedback circuit 42 e in the NC device 42. Note that the absolute position of the slide 3 cannot be obtained with high accuracy only by the encoder 39 because of the backlash of the drive system, the deflection of the press frame, the resolution limit of the encoder 39 itself, etc. A signal from the linear scale 33 is used as a feedback signal to the device 42.

  Further, an emergency stop circuit 45 is provided, and a stop signal from an emergency stop button (not shown), an abnormality detection signal from the NC device 42, an abnormality detection signal from the servo amplifier 43, and the like are input to the emergency stop circuit 45. The emergency stop circuit 45 has a power supply power supply 44, a servo amplifier 43, and a mechanical (non-excited) brake (braking means) 46 when all the signals such as the stop signal and the abnormality detection signal are “no abnormality”. A control signal is output to the switch 48 that closes the first normally open contact 47a and the second normally open contact 47b that are inserted between the first normally open contact 47a and the second normally open contact 47b. Here, the mechanical brake 46, which is not clearly shown in FIGS. 1 and 2, has a function of stopping the output shaft by pinching and restraining the output shaft of the servo motor 21 from the outside. It is.

  Incidentally, since the output signal from the linear scale 33 is a signal indicating the absolute position of the slide 3, in order to know at which position between the top dead center and the bottom dead center the slide 3 is currently located. Needs to know the current die height (the distance from the upper surface of the bolster 5 to the lower surface of the slide 3 at the bottom dead center of the slide 3). The current die height is obtained as follows. That is, first, the value of the linear scale 33 at the reference die height (set by the press manufacturer at the time of shipment) is set. Next, the die height adjusting motor is appropriately rotated to set the die height suitable for the mold to be used. At this time, the rotation of the slide adjustment motor is detected by the slide adjustment encoder, and the current die height is obtained by calculating how far the current die height is from the reference die height.

  The reference die height can be corrected periodically. In this correction method, the position of the slide 3 is measured with a linear scale 33 at predetermined time intervals, and the detection value of the linear scale 33 at the top dead center or the bottom dead center is obtained. The value obtained by subtracting the stroke and the value obtained by subtracting the position of the upper surface of the bolster 5 from the detected value itself at the bottom dead center is used as the actual die height.

  In the safe one-stroke mode by the electric servo press 1 having the above-described configuration, when the operator manually loads the workpiece into the mold and presses the start switch 41 when the top dead center of the slide 3 is stopped, the NC device In 42, the slide 3 is positioned based on the deviation between the target position based on the preset slide motion data and the current position input from the linear scale 33. In the servo amplifier 43, the pulse signal of the pulse coder 40 is used. The servo motor 21 is controlled so that the deviation between the calculated motor rotation speed and the speed command output from the NC device 42 based on the slide motion data becomes small. Thus, the slide 3 is moved from the top dead center to the bottom dead center at a predetermined speed, and after machining the workpiece near the bottom dead center, the slide 3 is continuously raised to the top dead center and stopped at the top dead center.

  Contrary to the speed command from the NC device 42, when the servo motor 21 runs away and the feedback signal exceeds a predetermined threshold, an abnormality detection signal is immediately sent from the output circuit 42d of the NC device 42 to the emergency stop circuit 45. Is output. As a result, the switch 48 is operated to open the first normally open contact 47a interposed between the power supply power supply 44 and the servo amplifier 43, and the power supply power supply 44 and the mechanical brake 46 The second normally open contact 47b inserted between the two is opened. As a result, the power supply to the servo motor 21 is cut off and the output shaft of the servo motor 21 is mechanically braked.

  Also, when the difference between the detected value from the linear scale 33 and the motion command value from the NC device 42 exceeds a predetermined threshold value, it is detected as a malfunction of the drive system, and immediately as described above. The power supply to the servo motor 21 is cut off and the output shaft of the servo motor 21 is mechanically braked.

  Further, in the system according to the present embodiment, the detected value from the pulse coder 40, the detected value from the linear scale 33, and the detected value from the encoder 39 correspond to the NC device 42 (corresponding to “monitoring means” of the present invention). By constantly monitoring in parallel, the risk of runaway of the servo motor 21 is avoided.

  According to the encoder 39 that detects the absolute angle of the main gear 38, it is possible to know where the slide 3 is located between the top dead center and the bottom dead center. That is, if the relationship between the absolute angle of the main gear 38 and the position of the slide 3 from the bottom dead center is stored in the form of a data table or expression, the linear scale 33 for detecting the absolute position of the slide 3 may break down, Even if the detected value indicating the current position of the slide 3 deviates from the actual value due to deviation, the current die height value in the NC device 42 is suddenly replaced with another value from the actual value. Even in this case, the main gear 38 rotates unexpectedly and unnaturally, and the abnormal state can be detected quickly.

  Further, if the slide position is differentiated with respect to time, the slide speed can be obtained, and if the absolute angle of the main gear 38 is differentiated with respect to time, the angular speed of the main gear 38 can be obtained. Therefore, the values of the slide speed and the main gear angular speed with respect to the absolute angle of the main gear 38 are obtained. If stored in a data table or expression, an abnormal state can be detected from these slide speeds or main gear angular speeds.

  Furthermore, when the encoder 39 itself breaks down due to vibration or the coupling provided on the mounting portion of the encoder 39 is broken, the slide position and slide speed obtained from the output of the encoder 39 are the output of the linear scale 33. The slide position and slide speed obtained from the above are significantly different from each other, whereby an abnormal state can be detected. In this case, which of the encoder 39 and the linear scale 33 is abnormal is determined by whether or not there is an unnatural change in the history of each output signal.

  The pulse signal from the pulse coder 40 built in the servo motor 21 is normally input to the servo amplifier 43 as described above, and the deviation between the motor rotation speed calculated from this pulse signal and the command speed is small. The servo motor 21 is controlled so that

  This pulse signal is further transferred from the servo amplifier 43 to the NC device 42. This pulse signal is generated one pulse each time the output shaft of the servo motor 21 rotates by a predetermined angle. Since the output shaft of the servo motor 21 is mechanically connected to the power transmission mechanism via a gear, a timing belt, or the like, the press angle per pulse can be obtained. If the number of pulses is reset at a timing corresponding to a predetermined press angle such as top dead center, the current press angle can be calculated by counting the number of pulses with a pulse counter.

  Therefore, by constantly comparing the absolute value of the press angle obtained by the encoder 39 with the absolute value of the press angle calculated from the pulse signal from the pulse coder 40, both the encoder 39 and the pulse coder 40 can be detected abnormally, and the electric motor Servo press runaway can be easily detected and serious accidents can be prevented.

  In addition, since it is possible to determine how many times the press angle moves per pulse, it is possible to easily detect abnormalities in both the encoder 39 and the pulse coder 40 and runaway of the electric servo press by constantly monitoring the amount of change in the press angle per pulse. Can be detected. In this case, it is only necessary to detect the pulse, and it is not necessary to count the number of pulses by the pulse counter or reset the number of pulses.

  Furthermore, by constantly comparing the angular velocity of the main gear calculated from the pulse signal from the pulse coder 40 with the angular velocity of the main gear obtained from the encoder 39, both the encoder 39 and the pulse coder 40 are abnormal and the runaway of the electric servo press is detected. can do.

  Further, since the slide position with respect to the press angle is uniquely determined when the die height is obtained, the absolute value of the slide position is further calculated from the absolute value of the press angle calculated from the pulse signal from the pulse coder 40, and the linear scale 33 is used. By constantly comparing with the absolute value of the slide position, abnormality of both the linear scale 33 and the pulse coder 40 can be detected, and the runaway of the electric servo press can be detected, so that a serious accident can be prevented.

  Further, since the amount of change in the slide position per pulse with respect to the press angle is obtained, it is easy to detect abnormalities in both the linear scale 33 and the pulse coder 40 as well as electric monitoring by constantly monitoring the amount of change in the slide position per pulse. Servo press runaway can be detected. In this case, the die height need not be known.

  As described above, according to the electric servo press 1 of the present embodiment, the detection values from the pulse coder 40, the linear scale 33, and the encoder 39 are constantly monitored in parallel by the NC device 42. An abnormal state is detected when there is a deviation in the detection value of the device, and the press is stopped in an emergency when this abnormality occurs. For example, an unexpected accident caused by a runaway of the slide 3 due to a disconnection, failure, disturbance, etc. of the position detection mechanism Can be prevented in advance.

  In the present embodiment, the description has been given of the pulse coder 40, the linear scale 33, and the encoder 39 provided with three types of detectors. However, when only the two types of detectors, the linear scale 33 and the encoder 39, are provided, The required purpose can be achieved.

  In the present embodiment, the encoder 39 detects the absolute angle of the main gear 38 fixed to the main shaft. However, the encoder 39 detects the rotation of the main shaft from the end of the main shaft. You can also. On the other hand, in a press of a type in which a main shaft is fixed and a main gear is rotatably supported on the main shaft, it is necessary to draw out rotation from the main gear through an intermediate gear or the like. There is also a method in which the rotation is taken out from the intermediate shaft, converted into the same rotation as the main gear via an intermediate gear or the like, and then detected by an encoder. According to this method, there is a disadvantage that the influence of backlash between the main gear and the main pinion enters, but there is an advantage that noise due to machining vibration hardly enters the encoder signal.

  In this embodiment, the example applied to the hand-in die in the safe one-stroke mode has been described. However, the technical idea of the present invention can be applied to other operation modes or other usage methods. Needless to say.

Side surface fragmentary sectional view of the electric servo press which concerns on one Embodiment of this invention. Rear partial sectional view of the electric servo press according to the present embodiment Control block diagram of electric servo press of this embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric servo press 3 Slide 5 Bolster 7 Screw shaft 11 Plunger 13 Triaxial link 21 Servo motor 27 Drive shaft 33 Linear scale 39 Encoder 40 Pulse coder 42 NC device 43 Servo amplifier 44 Power supply power supply 45 Emergency stop circuit 46 Mechanical brake 47a, 47b Normally open contact 48 Switch

Claims (2)

In the electric servo press that processes the workpiece by converting the rotational driving force of the servo motor into the vertical reciprocating motion of the slide via the power transmission mechanism,
From position detection means for detecting the absolute position of the slide, angle detection means for detecting the absolute angle of the main gear or main shaft in the power transmission mechanism, signals from the position detection means and angle detection means, or from the signals An electric servo press comprising monitoring means for monitoring a mutual shift amount of each calculated value to be calculated. In the electric servo press that processes the workpiece by converting the rotational driving force of the servo motor into the vertical reciprocating motion of the slide via the power transmission mechanism,
Position detecting means for detecting the absolute position of the slide, angle detecting means for detecting the absolute angle of the main gear or main shaft in the power transmission mechanism, and a pulse for detecting a pulse signal output in accordance with the rotation of the servo motor An electric servo comprising: a detection unit; and a monitoring unit that monitors each signal from the position detection unit, the angle detection unit, and the pulse detection unit or a mutual shift amount of each calculated value calculated from each signal. press.

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