JP2013029013A - Automatic penetration testing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic penetration testing machine capable of accurately applying a test load to a penetration rod.SOLUTION: An inventive automatic penetration testing machine 1 includes: a lifting stage 3 capable of ascending and descending along an erected support; a penetration rod 4 which is held by a chuck 5 provided in the lifting stage 3 and penetrates the ground as the lifting stage 3 descends; a load sensor 39 which detects a load applied to the penetration rod 4; a lifting motor 8 which is used for the operation of ascending/descending of the lifting stage 3, and applies an ascending force according to a torque command value to the lifting stage 3 to apply a load equal to the value made by subtracting the ascending force from the total weight of the lifting stage 3 as a test load to the penetration rod 4; and a control unit 50 which performs feedback control of the torque command value outputted to the lifting motor 8 on the basis of the deviation between the detection value by the load sensor 39 and a target test load value. According to such an arrangement, a required test load can be applied to the penetration rod 4 stably and accurately, thus improving reliability of the penetration test.

Description

  The present invention relates to an automatic penetration testing machine that penetrates a penetration rod into the ground and determines the hardness of the ground based on the penetration resistance.

  Conventionally, as an example of a penetrating test, an automatic penetrating tester that performs a Swedish sounding test is disclosed in Patent Document 1.

  The automatic penetration testing machine shown in Patent Document 1 has a penetration rod held by a chuck provided on a lifting platform, and is configured such that the lifting platform is raised and lowered by driving a lifting motor. Further, by the load open loop control, the lifting motor is driven with a torque command value set in advance by a calibration test, and a rising force is applied to the lifting platform. With this configuration, a load determined by (load based on the total weight of the lifting platform) − (lifting force of the lifting motor) is loaded on the penetrating rod as a test load.

JP 2004-92202 A

  However, the automatic penetration tester based on the above-described load open loop control cannot compensate for disturbances in the system, such as aging of components, and so on, so that the accuracy compensation of the load actually applied to the penetration rod is not perfect.

  The automatic penetration testing machine of the present invention has been created in view of the above problems, and is held by a lifting platform that can be lifted and lowered along a standing column and a chuck provided on the lifting platform, The penetrating rod that penetrates into the ground as it descends, the load sensor that detects the load applied to the penetrating rod, and the lifting platform are moved up and down, and the lifting force corresponding to the torque command value is applied to the lifting platform to A lift motor that loads the penetrating rod as a test load with a load obtained by subtracting the lifting force from the total weight, and a torque command that is output to the lift motor based on the deviation between the value detected by the load detection sensor and the target test load value And a control unit that feedback-controls the value.

  The control unit is preferably configured to drive and control the lifting motor by using both feedback control and feedforward control.

  Further, it is desirable that the control unit has built-in characteristic characteristic compensation means for converting an output value based on characteristic characteristic data of the load sensor.

  Further, it is desirable that the control unit includes a vibration preventing means for subtracting a torque command value output to the lifting motor in accordance with the acceleration of the lifting motor.

  The automatic penetration testing machine of the present invention is configured to feedback control the torque command value output to the lifting motor based on the actual load loaded on the penetration rod, so as to control the load applied to the penetration rod with high accuracy. A desired test load can be applied to the penetration rod, which contributes to the improvement of the reliability of the penetration test.

It is a perspective view of the automatic penetration testing machine of the present invention. It is a side view of the automatic penetration testing machine of the present invention. FIG. 3 is a partially cutaway cross-sectional view taken along line AA in FIG. 2. It is a principal part expansion partial notch sectional view which shows the structure of the chuck | zipper of the automatic penetration tester of this invention. It is a figure which shows the structure of the load sensor of the automatic penetration testing machine of this invention. It is a drive system block diagram of the raising / lowering motor by the control unit of the automatic penetration testing machine of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes an automatic penetration testing machine, which has a lifting platform 3 that can be moved up and down along a column 2. The lifting platform 3 includes a weight 3a having a predetermined weight, a rotation motor 6, a chuck 5 that can be rotated by the rotation of the rotation motor 6, and a chuck 5 that is held by the chuck 5 and rotates integrally. An intrusion rod 4 having a screw point 4b and an elevating motor 8 for elevating the elevating platform 3 are loaded.

  As shown in FIG. 2, the lifting platform 3 has a sprocket 7 that rotates along a guide chain 2 a that is vertically arranged along the column 2, and the sprocket 7 rotates along the guide chain 2 a. It is configured to move up and down. The penetrating rod 4 can be loaded with a load of 1 KN based on the lifting platform 3 and the total weight loaded on the lifting platform 3.

  As shown in FIG. 3, the sprocket 7 is connected so as to rotate integrally with the transmission shaft 12 via the planetary gear mechanism 11. A drive gear 13 is attached to the tip of a drive shaft 8a capable of forward and reverse rotation of the elevating motor 8 so as to rotate integrally. Further, an intermediate gear 14 and a transmission gear 15 are meshed with the drive gear 13 in order, and the drive of the lifting motor 8 is transmitted to the transmission shaft 12.

  The transmission gear 15 is a hollow cylinder and has outer teeth on its outer peripheral surface. The one-way clutch 16 is press-fitted into the transmission gear 15 so as to rotate integrally with the transmission gear 15 and is rotatably supported by the transmission shaft 12. When the lifting / lowering motor 8 is driven to rotate the sprocket 7 in the direction in which the lifting / lowering base 3 is going to rise by the action of the first one-way clutch 16 (for convenience, this driving is assumed to be forward rotation driving) The drive of the motor 8 is transmitted to the transmission shaft 12. For this reason, a load determined by (load 1 KN based on the total weight of the elevator 3) − (ascending force according to the output torque of the elevator motor 8) is applied to the penetrating rod 4 as a test load.

  On the other hand, when the elevating motor 8 is driven (for the sake of convenience, this driving is set as reverse driving), the one-way clutch 16 rotates idly. For this reason, it is possible to create a state where the drive of the lifting motor 8 is not transmitted to the transmission shaft 12, and the penetrating rod 4 can be loaded with 1 KN (maximum test load) based on the total weight of the lifting platform.

  A rotary encoder 17 is attached to the transmission shaft 12 and outputs a pulse signal accompanying the rotation of the sprocket 7. Then, the main control device 80 of the control unit 50, which will be described in detail later, processes the pulse signal, and calculates the penetration amount and penetration speed of the penetration rod 4 based on the elevation amount and elevation speed of the lifting platform 3.

  The elevating motor 8 is an induction motor, and is driven and controlled by an inverter control device 60 described later in detail. A main driving pulley 18 is attached to the rear end of the drive shaft 8a of the elevating motor 8 so as to be integrally rotatable. A driven pulley 19 is disposed at a position spaced from the main pulley 18 by a predetermined distance, and an endless belt 20 is wound around the pulleys 18 and 19. A rotary encoder 21 is attached to the driven pulley 19 as acceleration detecting means for the lifting motor 8, and is configured to detect a pulse signal associated with the rotation of the drive shaft 8 a of the lifting motor 8. . The pulse signal from the rotary encoder 21 is output to the inverter control device 60 and the main control device 80 of the lifting motor 8.

  In addition, even if it is the structure provided with the drive control part according to this using an AC servomotor instead of an induction motor, an equivalent function is realizable.

  As shown in FIG. 4, the chuck 5 is inserted into a hollow chuck shaft 31 rotatably supported by bearings 45, 46, 47, and 48, and a machine key (not shown) is inserted into the chuck shaft 31. And a flange-type sleeve 32. The sleeve 32 is constantly biased upward by a spring 33 and is configured to be movable while sliding on the outer peripheral surface of the chuck shaft 31. On the other hand, it is configured to rotate integrally with the chuck shaft 31 in the circumferential direction. The chuck shaft 31 is provided with a storage hole that can store the steel ball 34 at a position that divides the outer periphery into three equal parts. The steel ball 34 is fitted into an engaging groove 4 c formed on the outer peripheral surface of the penetrating rod 4 to hold the penetrating rod 4. Further, the inner diameter of the upper portion of the sleeve 32 is formed to be larger than the inner diameter of the chuck shaft 31, and when the sleeve 32 is manually pushed down against the bias of the spring 33, the steel ball 34 is engaged with the penetrating rod 4. Detach from the groove 4c. In this state, when the chuck shaft 31 is rotated together with the sleeve 32 and the steel ball 34 is moved to a position where the engagement groove 4c of the penetration rod 4 is not formed, the penetration rod 4 and the chuck shaft are removed even if the hand is released from the sleeve 32. The engagement with 31 is released.

  A rotating motor 6 is loaded on the elevator 3. The rotation motor 6 is an induction motor, and is driven and controlled by an inverter control device (not shown) by attaching a rotary encoder 7 to the rear end of the drive shaft 6a. A main sprocket 36 is attached to the tip of the drive shaft 6 a of the rotation motor 6 via a one-way clutch 35. On the other hand, a driven sprocket 37 is attached to the lower end of the chuck shaft 31, and an endless chain 38 is wound around these sprockets 36, 37 to transmit the rotational drive of the motor 6 for rotation to the chuck shaft 31, thereby 4 rotates.

  Here, as shown in Japanese Industrial Standard A1221, the screw point 4b at the tip of the penetrating rod 4 has a drill shape in which one twist is applied to a length of 200 mm. Therefore, the one-way clutch 35 is operated when the rotation motor 6 is driven in the direction in which the penetration rod 4 is screwed into the ground in accordance with the twist of the screw point 4b (hereinafter, this drive is assumed to be forward rotation for convenience). Since the drive is transmitted to the main sprocket 35, the penetrating rod 4 rotates. On the other hand, when the rotation motor 6 is driven in the opposite direction (hereinafter referred to as “reverse drive” for convenience), the penetrating rod 4 does not rotate. This structure is the same as that shown in Japanese Patent Application Laid-Open No. 2005-27331.

  As shown in FIG. 5, a washer type load cell 39 is inserted into the chuck shaft 31 as an example of a load sensor. The washer-type load cell 39 includes a pressure receiving portion 41 formed on the lower surface of the sensor body 40 at equal intervals in the circumferential direction, and a support portion formed on the upper surface of the sensor body 40 at equal intervals in the circumferential direction. 42 and a strain gauge 43 attached to the sensor main body 40. With this configuration, the thrust load actually applied to the penetrating rod 4 is transmitted to the pressure receiving portion 41 via the angular ball bearings 45 and 46 and the cylindrical roller bearing 47 that support the chuck shaft 31, and the support portion 42 receives the pressure accordingly. The sensor body 40 becomes distorted with respect to the plate 44 as a fulcrum. When the strain gauge 43 detects this strain, the load applied to the penetrating rod 4 can be detected with high accuracy.

  As shown in FIG. 6, the control unit 50 of the automatic penetration testing machine 1 includes an inverter control device 60 that drives and controls the lifting motor 8, an inverter control device (not shown) that drives and controls the rotation motor 6, and A load control device 70 that performs feedback control on the inverter control device 60 based on the detection signal of the washer-type load cell 39; a main control device 80 that sends various commands to the inverter control device 60 and the load control device 70; The storage device 90 stores various parameters and control amount data, and the I / O interface 100.

  The inverter control device 60 performs torque control of the lifting motor 8 with a torque command value input from the load control device 70. The configuration is such that a three-phase AC power source (not shown) is converted to DC by a converter circuit 61, and a DC voltage smoothed by a smoothing capacitor 62 is converted to AC voltage by an inverter circuit 63, thereby changing a variable voltage. -It is comprised so that a frequency may be given to the motor 8 for raising / lowering. Then, the arithmetic circuit 65 (MPU) executes the motor current feedback control based on the outputs of the current detector 64 and the rotary encoder 21, thereby enabling operation by the vector control method. As described above, the inverter control device 60 controls torque and speed control by controlling the rotation speed and output torque of the lifting motor 8 by the vector control method in which the rotary encoder 21 is combined with the lifting motor 8. . During speed control, the elevating motor 8 is driven and controlled with a speed command value input from the main controller 80. The inverter control device 60 can set speed limits and torque limits, and is configured to execute drive control within a range not exceeding these set values.

  The load control device 70 determines a torque command value to be input to the inverter control device 60 so that the load command value input from the main control device 90 is added to the penetrating rod 4, and the washer load cell A PID control circuit 71 that executes PID control as an example of feedback (FB) control based on the output of 39 is incorporated. This PID control is a combination of proportional control, integral control, and derivative control.

  Therefore, the manipulated variable y (t) of the torque command value is calculated in order to bring the output value of the washer-type load cell 39 close to the target value based on Equation 1 above. The first term on the right side is proportional control, the second term is the integral control, and the third term is the manipulated variable by differential control. The manipulated variable y (t) is calculated by adding these manipulated variables. Further, e (t) is a deviation between the output value and the target value, Kp is a proportional constant for proportional control, Ki is a proportional constant for integral control, Kd is a proportional constant for differential control, and Kp, Ki, Kd Is set to the value with the best response by tuning.

  Further, the load control device 70 incorporates a feedforward compensation circuit 72 for executing feedforward (FF) control in combination with feedback control. A torque command value corresponding to a test load is stored in the storage device 90. When a load command is issued from the main control device 80, the feedforward compensation circuit 72 stores a torque command value corresponding thereto. It is read from the device 90 and given to the inverter control device 60 as an initial value. Moreover, the control amount data by the PID control circuit 71 is generated in the storage device 90 as a new torque command value corresponding to the load command. Then, the generated torque command value and the control amount data output from the PID control circuit 71 are added and output to the inverter control device 70 as a torque command value. As described above, the feedforward compensation circuit 72 is configured to suppress in advance disturbance of feedback control due to a disturbance factor.

  Further, since the washer type load cell 39 is inserted so as to be sandwiched from both sides, unique characteristics occur. Therefore, the load control device 70 has a built-in characteristic characteristic compensation circuit 73, which converts an input value (detected value) based on a correction parameter set according to the characteristic characteristic of the washer load cell 39 and outputs the converted value. Is configured to do.

The load control device 70 has a built-in vibration prevention circuit 74. The vibration prevention circuit 74 calculates the acceleration of the lifting motor 8 from the output of the rotary encoder 21, and subtracts the control amount data from the PID control circuit 71 and the feedforward compensation circuit 72 in accordance with the acceleration, thereby controlling the inverter control device. 60 is output as a torque command value. Thereby, the raising / lowering motor 8 can drive smoothly, and a vibration can be prevented.

  The main controller 80 is configured to calculate test results in addition to issuing various commands to the load controller 70 or the inverter controller 60. When the Swedish sounding test is executed by the automatic penetration testing machine 1, a load is applied to the penetration rod 4 in stages in the self-sinking penetration test. Then, the penetration amount of the penetration rod 4 under each load is calculated based on the output value of the rotary encoder 17 attached to the lifting platform 3. In the self-sinking penetration test, since the penetration rod 4 is not rotated, the rotation motor 6 is not driven. On the other hand, in the rotation penetration test, the elevating motor 8 is driven in the reverse direction, and the rotation motor is driven in a state where a load of 1 KN based on the mass of the elevating table 3 is applied to the penetration rod, thereby causing the penetration rod 4 to rotate and penetrate. . Then, the number of revolutions required for penetrating the penetrating rod 4 by 25 cm is calculated based on the output of the rotary encoder 7. These test results are informed to the operator by display on a monitor or printing out.

  According to the automatic penetration testing machine 1 of the present invention, the detected value of the washer-type load cell 39 by the load control device 70 in addition to the torque control by the vector control method of the inverter control device 60 for the lifting motor 8. By performing the feedback control based on the test load, it is possible to control the test load at high speed and with high accuracy.

  Since the automatic penetration testing machine 1 has all the functions for realizing load control, penetration speed control and load detection for the penetration rod, it is not limited to the Swedish sounding test but can be used for automation of other penetration tests. Can be used as a contributing base machine.

  As an example of the penetration test, the Japan Geotechnical Society Standard (JGS1431) Portable Cone Penetration Test statically pushes the cone into the ground and reads the penetration resistance at every predetermined depth while penetrating the cone at a predetermined penetration speed. Is. Therefore, the cone is attached instead of the screw point 4b of the penetrating rod 4, and the cone control is performed at a predetermined penetrating speed by switching the control mode based on the vector control method of the inverter control device 60 from the torque control mode to the speed control mode. It becomes possible to penetrate into the ground. Further, by reading the detection value of the washer type load cell 39 while monitoring the penetration depth of the cone with the rotary encoder 17, it becomes possible to detect the penetration resistance at every predetermined depth. Therefore, the automatic penetration testing machine 1 can realize the automation of the portable cone penetration test.

DESCRIPTION OF SYMBOLS 1 Automatic penetration test machine 2 Support | pillar 2a Guide chain 3 Lifting base 3a Weight 4 Penetrating rod 4b Screw point 4c Engaging groove 5 Chuck 6 Motor for rotation 7 Rotary encoder 6a Drive shaft 8 Lifting motor 8a Drive shaft 11 Planetary gear mechanism 12 Transmission Shaft 13 Drive gear 14 Intermediate gear 15 Transmission gear 16 One-way clutch 17 Rotary encoder 18 Drive pulley 19 Drive pulley 20 Endless belt 21 Endless belt 21 Chuck shaft 32 Sleeve 33 Spring 34 Steel ball 35 One-way clutch 36 Drive sprocket 37 Drive sprocket 38 Endless chain 39 Washer type load cell 40 Load cell main body 41 Pressure receiving portion 42 Support portion 43 Strain gauge 44 Pressure receiving plate 45, 46 Angular ball bearings 47, 48 Cylindrical roller bearing 50 Control unit 60 Inverter control device 61 Over capacitor circuit 62 smoothing capacitor 63 inverter circuit 64 a current detector 65 arithmetic circuits (MPU)
70 Load control device 71 PID control circuit 72 Feed forward compensation circuit 73 Inherent characteristic compensation circuit 74 Vibration prevention circuit 80 Main control device 90 Storage device 100 I / 0 interface

Claims (4)

A lifting platform that can be moved up and down along a standing column;
A penetrating rod that is held by a chuck provided on the lifting platform and penetrates into the ground as the lifting platform is lowered;
A load sensor for detecting the load applied to the penetrating rod;
A lifting motor that lifts and lowers the lifting platform and applies a lifting force according to the torque command value to the lifting platform and loads the penetration rod as a test load by subtracting the lifting force from the total weight of the lifting platform;
An automatic penetration testing machine comprising: a control unit that feedback-controls a torque command value output to a lifting motor based on a deviation between a value detected by a load detection sensor and a target test load value.   The automatic penetration testing machine according to claim 1, wherein the control unit is configured to drive and control the lifting motor by using both feedback control and feedforward control.   The automatic penetration testing machine according to claim 1 or 2, wherein the control unit has a built-in unique characteristic compensation means for converting an output value based on the unique characteristic data of the load sensor.   The automatic control unit according to any one of claims 1 to 3, wherein the control unit includes vibration preventing means for subtracting a torque command value output to the lifting motor in accordance with acceleration of the lifting motor. Penetration testing machine.

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