JP2006258574A - Loading device and loading method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a load waveform by avoiding generation of torque shortage or resolution shortage, when performing a load test or a plastic deformation processing. <P>SOLUTION: An elastic body 11 is integrated into a loading rod 3 moving forward and backward by rotation of a servomotor. The elastic body 11 has a spring constant wherein the maximum loading frequency becomes higher than a prescribed frequency corresponding to a loading load to an object, and an effective resolution at the displacement control time satisfies a prescribed resolution. A displacement gage 13 measures displacement of the elastic body 11, and a motor control circuit 15 performs feedback control of the rotation of the servomotor based on the displacement of the elastic body 11. Hereby, even when a load domain loaded by a static load test or by a static pressurization processing is different greatly, a rotational frequency wherein the servomotor can show a sufficient torque in loading can be guaranteed. In addition, stable load control can be performed also in an electric-oil actuator 1 based on displacement control in the static load test or in the static pressurization processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a loading apparatus and a loading method that are applied when performing various load tests or when performing pressure processing such as plastic deformation processing of a press machine. Note that “loading” in the present invention is a broad concept including not only loading in a narrow sense for the purpose of a load test but also pressing and applying force.

  In general, as an actuator for loading an object (load), a method of rotating a ball screw directly connected to a motor (electric motor) and linearly moving a nut is called an electric actuator. In addition, as shown in FIG. 5, there is also used a system in which a two-way rotating two-way discharge hydraulic pressure pump directly connected to a motor is rotated forward and backward to discharge hydraulic pressure in two directions and linearly move the rod of the hydraulic cylinder. This is referred to as an electric-hydraulic actuator (abbreviated as electro-oil actuator). This is also a type of direct drive type electric actuator that directly drives a hydraulic cylinder by converting the rotational force of the motor into hydraulic energy by a hydraulic pump without using a control valve.

  However, unlike a general hydraulic device having an independent hydraulic source, the direct drive type actuator directly reflects the output characteristics of the servo motor in the actuator characteristics. Therefore, this device is generally good at position control but is not suitable for load control. This is because when the load is constant and the object hardly displaces, the servo motor must be controlled at a very low rotation, and thus the necessary torque and control resolution cannot be fully exhibited.

  For example, as shown in FIG. 6B, when the load change of the triangular wave is performed, if the object is not an elastic body but an extremely hard substance (for example, metal, concrete, etc.), the actuator has a sufficient operation stroke. The necessary load is reached without being secured. Therefore, the motor can work only within the extremely low speed rotation range as shown in FIG. 6A, resulting in insufficient torque and insufficient resolution. As shown in FIG. On the other hand, the waveform of the output load becomes unstable.

  This is because servo motors exhibit excellent responsiveness only within the range of high-speed rotation near the rated speed, but the torque itself is insufficient in the extremely low-speed rotation region, resulting in torque resolution. This is because it seems to have fallen.

  In addition, when the period of the triangular wave is lengthened, that is, when the frequency is low, and when the load fluctuation is performed at a high frequency by shortening the period of the triangular wave, the motor characteristics change, and the output load for the command signal changes. The waveform is greatly deteriorated.

In order to improve the measurement accuracy in the minute region of the loaded load, in one loading device, the displacement control is performed in the minute region of the loaded load, and the load control is performed in the region exceeding the loaded load (hereinafter referred to as displacement / load control). (Referred to as Patent Document 1).
JP-A-9-250978

  However, this combined displacement / load control method is intended to improve the measurement accuracy in a very small area, and the target loading device is also assumed to be only a hydraulic servo control system composed of a hydraulic cylinder and a servo valve. Therefore, this combined displacement / load control method is a fundamentally different invention from the present invention characterized in that the displacement is converted into a load by one elastic body from zero to the maximum load required by the object.

  In view of such circumstances, an object of the present invention is to provide a loading device and a loading method that can avoid a situation in which insufficient torque or insufficient resolution occurs and can stabilize a load waveform.

First, the invention of the loading device according to claim 1 has a loading rod that advances and retreats by the rotation of a motor, and the loading device in which the elastic body is incorporated in the loading rod described above, the elastic body is applied to the loading load on the object. Accordingly, the maximum loading frequency is equal to or higher than a predetermined frequency, and at the same time, the effective resolution at the time of displacement control has a spring constant that satisfies the predetermined resolution.
The invention of the loading device according to claim 2 is characterized in that the rotation of the motor is feedback-controlled based on the amount of displacement of the elastic body.
According to a third aspect of the present invention, there is provided a loading device including a loading rod that advances and retreats by rotation of a motor, and the elastic body is incorporated in the loading rod described above, wherein the elastic body has a displacement amount of the loading rod described above. A proportional load is applied to the object.
The invention of the loading device according to claim 4 is characterized in that the displacement amount of the elastic body is fed back to a motor control circuit, and the rotational direction, rotational speed and rotational torque of the motor are servo-controlled.
The invention of the loading device according to claim 5 is characterized in that the elastic body can vary a spring constant.
Further, the invention of the loading device according to claim 6 is characterized in that the load rod described above is advanced and retracted by a fixed-capacity two-way discharge hydraulic pump that operates by receiving the rotational force of a two-way rotation type motor.
The invention of the loading device according to claim 7 is characterized in that the load rod described above is advanced and retracted by a variable capacity two-way discharge type hydraulic pump that operates by receiving the rotational force of a one-way rotation type motor.
Further, the invention of the loading method according to claim 8 is to prepare an elastic body having a plurality of types of spring constants when the loading rod is advanced and retracted by the rotation of the motor and loaded onto the object. The elastic body is selected and incorporated in the loading rod so that the maximum loading frequency becomes equal to or higher than the predetermined frequency according to the loading load, and the effective resolution at the time of displacement control satisfies the predetermined resolution. To do.
Further, the invention of the loading method according to claim 9 is to prepare an elastic body having a plurality of types of spring constants when the loading rod is advanced and retracted by the rotation of the motor and loaded on the object. The elastic body is selected so that the effective resolution at the time of displacement control of the elastic body satisfies a predetermined resolution in accordance with the load.
Here, any type of motor can be used as long as it can control the rotational direction, rotational speed, and rotational torque. For example, in addition to a servo motor, an induction motor, a synchronous motor, a DC motor, or the like can be employed.

  According to the present invention, since the elastic body is incorporated in the loading rod, even if the load area to be loaded is greatly different due to the static load test or the static pressure processing, the rotation at which the motor can exert sufficient torque in the loading is performed. It is possible to guarantee the number. Therefore, in a static load test or static pressure processing, it is possible to avoid a situation in which insufficient torque or insufficient resolution occurs, and to stabilize the load waveform.

  Furthermore, since this elastic body has an appropriate spring constant corresponding to the load applied to the object, stable load control is possible even with actuators based on displacement control in dynamic load tests and dynamic pressurization. It can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram showing an embodiment of a loading apparatus according to the present invention.

  As shown in FIG. 1, the loading device has a direct drive type electro-oil actuator 1, and the electro-oil actuator 1 includes a cylinder 2, a piston 4, a loading rod 3, as shown in FIG. 2. The hydraulic pump 5, the pipes 6 and 7, the servo motor 9, and a compensation circuit 12 that compensates for the volume difference between the cap side (upper side in FIG. 2) and the head side (lower side in FIG. 2) of the hydraulic cylinder. That is, the electro-oil actuator 1 has a cylinder 2, and a piston 4 is slidably supported in the cylinder 2. Further, a loading rod 3 is attached to the piston 4 in such a manner that its tip protrudes from the cylinder 2 to the outside. The cylinder 2 is provided with a fixed displacement two-way discharge type hydraulic pump 5. Two pipes 6 and 7 are connected to the hydraulic pump 5 so as to allow hydraulic oil to pass between the hydraulic pump 5 and a compensation circuit 12 is connected between the pipes 6 and 7. Yes. Therefore, the compensation circuit 12 compensates for the volume difference between when the piston 4 moves to the cap side (upper side in FIG. 2) and when it moves to the head side (lower side in FIG. 2), thereby smoothly moving the piston 4 forward and backward. be able to. Further, a two-direction (forward / reverse direction) rotation type servo motor 9 is attached to the hydraulic pump 5. The servo motor 9 can freely control the rotation direction, the rotation speed, and the rotation torque.

  By the way, as shown in FIG. 1, the loading rod 3 is separated into a front portion 3a and a rear portion 3b, and an elastic body 11 is elastically placed between the front portion 3a and the rear portion 3b on the loading rod 3. It is detachably incorporated in a form that allows it to expand and contract. A displacement meter 13 is attached to the loading rod 3 so as to measure the amount of increase / decrease in the distance between the front portion 3a and the rear portion 3b, that is, the displacement amount of the elastic body 11. Furthermore, a motor control circuit 15 is attached to the electro-oil actuator 1 so that a control signal corresponding to the displacement amount output from the displacement meter 13 can be output to the electro-oil actuator 1.

  As a specific example of the loading apparatus having such a configuration, the one shown in FIG. 3 can be considered. Here, a spiral spring is employed as the elastic body 11, and a non-contact displacement meter comprising a main body 13a having a laser light emitting portion and a laser light receiving portion and a laser reflecting plate 13b is used as the displacement meter 13. Further, a load meter 16 such as a load cell is attached to the tip of the loading rod 3 for load confirmation.

  Therefore, when performing a static load test or a static pressure process using this loading apparatus, the servo motor 9 is properly adjusted as shown in FIG. 2 with the object placed in front of the loading rod 3. By rotating and operating the hydraulic pump 5, hydraulic oil is supplied from the hydraulic pump 5 through the pipe 6 into the cylinder 2, and is supplied from the cylinder 2 through the pipe 7 to the hydraulic pump 5. to recover. Then, since the piston 4 slides to the head side (lower side in FIG. 2), the loading rod 3 protrudes and comes into contact with the object, and the object is pressed by the loading rod 3 and receives a static load.

  At this time, if the object is hard, the elastic body 11 receives the compressive force and contracts. Therefore, even if the object is hard, a sufficient operation stroke can be secured for the electro-oil actuator 1. As a result, even if the load areas are greatly different, the rotation of the servo motor 9 is stabilized and sufficient torque can be exhibited. Therefore, in a static load test or static pressure processing, it is possible to avoid a situation in which insufficient torque or insufficient resolution occurs and to stabilize the load waveform as shown in FIGS. 4 (a) and 4 (b).

  The displacement meter 13 measures the displacement amount of the elastic body 11 and outputs the displacement amount to the motor control circuit 15. In response to this, the motor control circuit 15 calculates an output load from the displacement amount of the elastic body 11 in accordance with Hooke's law, and feedback-controls the rotation of the servo motor 9 based on this output load. That is, when the output load calculated by the motor control circuit 15 is smaller than the specified output load, the servo motor 9 is rotated forward to further protrude the loading rod 3. On the other hand, when the output load calculated by the motor control circuit 15 is larger than the specified output load, the servo motor 9 is driven to reversely rotate the loading rod 3 to retract the loading rod 3. Therefore, a constant load can always be applied to the object.

  On the other hand, when performing a dynamic load test or dynamic pressurization using this loading device, first, an elastic body 11 having an appropriate spring constant corresponding to the loading load on the object is selected and the loading rod 3 is selected. Incorporate into. Here, the appropriate spring constant according to the load applied to the object means that the maximum load frequency (that is, the maximum load frequency that can be loaded with a certain load) is a predetermined frequency according to the load applied to the object. At the same time, it means a spring constant such that the effective resolution during displacement control satisfies a predetermined resolution. That is, when the loading load on the object increases, as shown in FIG. 7, the effective loading resolution tends to decrease at the same time as the maximum loading frequency decreases. As the spring constant of the elastic body 11 increases, for example, 366 N / mm, 735 N / mm, and 1225 N / mm, the displacement amplitude decreases even with the same loading load. As a result, the maximum loading frequency increases. While there is an advantage that it is possible to cope with the frequency, the effective resolution for controlling the electro-oil actuator 1 is increased, which causes a disadvantage that the control becomes unstable. Therefore, the effective resolution is made as small as possible with respect to the required loading frequency by appropriately setting the spring constant of the elastic body 11 according to the loading load.

  At this time, it is necessary to set the advance / retreat speed of the electro-oil actuator 1 to a speed having a margin from the maximum load speed. This is because the amount of forward / backward displacement is small when loading directly on the object, but the speed of the loading rod 3 is increased by the amount of deflection of the elastic body 11 because the elastic body 11 is interposed. As a result, unless the advance / retreat speed of the electro-oil actuator 1 is set faster than the advance / retreat speed of the loading rod 3, the loaded load is insufficient.

  Thus, in a state where the elastic body 11 having an appropriate spring constant corresponding to the load applied to the object is incorporated in the load rod 3, the object is installed in front of the load rod 3, and the servo motor 9 is moved in the forward and reverse directions. The hydraulic pump 5 is actuated by rotating alternately. Then, since the piston 4 slides alternately in both directions (the vertical direction in FIG. 2), the loading rod 3 repeatedly protrudes and retreats and intermittently contacts the object, and the object is pressed by the loading rod 3 and moves. Under the load. At this time, since the elastic body 11 has an appropriate spring constant corresponding to the load applied to the object, the electro-oil actuator 1 based on displacement control in the dynamic load test and the dynamic pressurizing process. However, stable load control can be performed.

  In this way, the optimum rotation region of the motor can always be used up by appropriately replacing the elastic body with an appropriate spring constant corresponding to the loaded load. Therefore, it is possible to perform a physically stable dynamic load test and dynamic pressurization rather than feedback control that relies solely on gain adjustment by conventional signal processing.

  Further, if an elastic body 11 having an air spring or a variable spring constant such as a combination of an accumulator and an oil damper is employed, gain adjustment can be performed in real time even during load control.

  In the above-described embodiment, the electro-oil actuator 1 having a structure for moving the loading rod 3 indirectly by driving the hydraulic pump 5 by the servo motor 9 has been described. However, the rack-and-pinion mechanism ( The loading rod 3 may be mechanically advanced and retracted by the servo motor 9 with a ball screw (not shown) or the like interposed therebetween.

  Further, the present invention can be applied to a loading device using a hydraulic servo valve. In this case, it is possible to effectively improve the instability of the operation due to the fluctuation of the spring constant during loading of the loading target.

  Further, in the above-described embodiment, as shown in FIG. 2, the electro-oil actuator 1 in which the fixed displacement two-direction discharge hydraulic pump 5 is combined with the two-direction rotation type servo motor 9 has been described. As shown, the electro-oil actuator 1 can be configured by combining a variable-capacity two-way discharge type hydraulic pump 5 having a rotary swash plate with a one-way rotation type servo motor 9.

  Moreover, although the case where the electro-oil actuator 1 was used was demonstrated in the above-mentioned embodiment, an electric actuator can be substituted. Further, the medium for transmitting the rotational force of the servo motor 9 as a driving source to the loading rod 3 of the cylinder 2 is not limited to oil, and any medium may be used as long as it is an incompressible fluid (liquid or gas). For example, water can be used as a medium.

It is a conceptual diagram which shows one Embodiment of the loading apparatus which concerns on this invention. It is a conceptual diagram which shows an example of the electro-oil actuator of the loading apparatus shown in FIG. It is sectional drawing which shows the specific example of the loading apparatus which concerns on this invention. It is a graph which shows the load feedback loading waveform of the loading apparatus shown in FIG. It is a conceptual diagram which shows an example of the electro-oil actuator of a direct drive system. It is a graph which shows the load feedback loading waveform of the electro-oil actuator shown in FIG. It is a graph showing the relationship between a loading load, the maximum loading frequency, and effective resolution by using a spring constant as a parameter. It is a conceptual diagram which shows another example of the electro-oil actuator of the loading apparatus which concerns on this invention.

Explanation of symbols

1 ... Electro-oil actuator 2 ... Cylinder 3 ... Loading rod 3a ... Front 3b ... Rear 4 ... Piston 5 ... Hydraulic pump 6, 7 ... Piping 9 ... Servo motor (motor)
11 …… Elastic body 13 …… Displacement meter 15 …… Motor control circuit

Claims (9)

It has a loading rod that moves forward and backward by the rotation of the motor,
In the loading device in which an elastic body is incorporated in the load rod described above,
The elastic body has a spring constant such that an effective resolution at the time of displacement control satisfies a predetermined resolution at the same time that the maximum loading frequency becomes equal to or higher than a predetermined frequency according to the load applied to the object. A loading device.   The loading device according to claim 1, wherein the rotation of the motor is feedback-controlled based on a displacement amount of the elastic body. It has a loading rod that moves forward and backward by the rotation of the motor,
In the loading device in which an elastic body is incorporated in the load rod described above,
The said elastic body applies the load proportional to the displacement amount of the load rod mentioned above to the target object, The loading apparatus characterized by the above-mentioned.   4. The loading apparatus according to claim 3, wherein the displacement amount of the elastic body is fed back to a motor control circuit, and the rotation direction, rotation speed and rotation torque of the motor are servo-controlled.   The loading device according to claim 1, wherein the elastic body has a variable spring constant.   6. The loading apparatus according to claim 1, wherein the load rod is advanced and retracted by a fixed displacement two-way discharge hydraulic pump that operates by receiving the rotational force of a two-way rotation type motor.   6. The loading apparatus according to claim 1, wherein the load rod is advanced and retracted by a variable capacity two-way discharge type hydraulic pump that operates by receiving a rotational force of a one-way rotation type motor. When loading the object by moving the loading rod back and forth by the rotation of the motor,
Prepare an elastic body with multiple types of spring constants,
The elastic body is selected and incorporated into the loading rod so that the maximum loading frequency becomes equal to or higher than the predetermined frequency according to the loading load on the object, and at the same time, the effective resolution at the time of displacement control satisfies the predetermined resolution. A loading method characterized by that. When loading the object by moving the loading rod back and forth by the rotation of the motor,
Prepare an elastic body with multiple types of spring constants,
The loading method according to claim 1, wherein the elastic body is selected so that an effective resolution at the time of displacement control of the elastic body satisfies a predetermined resolution in accordance with a loading load on the object.

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