Axial force measuring device for fastening bolts, and method for measuring the axial force of fastening bolts using the coaxial force measuring device.

Abstract

To provide a fastening bolt axial force measuring device capable of reducing a human burden during measurement by automating some of exploration operations during ultrasonic axial force measurement, adjusting easily and automatically to a positive contact posture in which a probe is accurately inclined to face a biased inclined surface of a bolt end, which has individual differences, and is brought into contact with appropriate pressing force, and improving accuracy of axial force measurements.SOLUTION: A fastening bolt axial force measuring device includes: a horizontal mounting base at a leading end of a robot arm; a probe body that is placed below the horizontal mounting base and measures a bolt length from an end face of a fastening bolt using an ultrasonic transmission and reception function; and a connecting spring that is interposed between the horizontal mounting base and the probe body and presses the probe body against the end face of the fastening bolt.SELECTED DRAWING: Figure 2

Description

Technical Field

[0007] ,

[0001] The present invention relates to an axial force measuring device for fastening bolts that fasten fastening members to each other, and a method for measuring the axial force of fastening bolts using the same axial force measuring device.

Background Art

[0002] Conventionally, for a fastening structure configured by fastening fastening members such as wheels and brake disks of a rail vehicle with fastening bolts, in order to prevent accidents such as the fastening bolts loosening or disengaging due to vibrations and impacts during running, or thermal distortion generated in the fastening members, robustness and reliability are required to ensure the fastening state with a plurality of fastening bolts at a high axial force.

[0003] In such a fastening structure, in order to evaluate and inspect the fastening force between the fastening members in the fastened state by the fastening bolts, the axial force of the fastening bolts is measured.

[0004] The methods for measuring the axial force of fastening bolts are roughly classified into a torque formula axial force measurement method that measures and calculates the axial force from the correlation with the tightening torque of the bolt (for example, see Patent Document 1), and an ultrasonic measurement method that measures and calculates the axial force from the correlation of the elongation difference of the bolt before and after tightening (for example, see Patent Documents 2 to 4).

[0005] The torque formula axial force measurement method of Patent Document 1 is a method of indirectly converting to the axial force by measuring the torque applied to the bolt as the amount of rotation of the bolt during tightening of the fastening members, and has the merit of being easily implemented.

[0006] However, the torque formula axial force measurement method has a demerit that it is difficult to cope with torque deviations generated during tightening due to minute individual differences in the fastening bolts such as thread shape and end face shape generated during the cutting manufacturing process, etc., and doubts arise about the authenticity of the measured values detected, and the reliability of the axial force measurement naturally decreases.

[0007] In this regard, the ultrasonic measurement method described in Patent Documents 2 to 4 has the advantage of enabling highly reliable axial force measurement because it involves applying a probe that emits and emits ultrasonic waves to the end face of the bolt head of the fastening bolt, directly measuring the bolt length before and after fastening, calculating the elongation of the bolt as the difference, and calculating the axial force from this elongation. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-141973 [Patent Document 2] Japanese Patent Application Publication No. 4-2936 [Patent Document 3] Japanese Patent Application Publication No. 10-86074 [Patent Document 4] Japanese Patent Publication No. 2019-128193 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, these conventional ultrasonic measurement methods had the potential to impose a heavy workload on operators during axial force measurement, and to result in variations in measurement accuracy due to the inability to accurately perform exploration operations under the optimal conditions necessary for axial force measurement.

[0010] In other words, ultrasonic axial force measurement involves several exploration operations, such as a medium settling operation in which a coupling medium to improve the transmission of ultrasonic waves from the transducer is applied to the bolt end and allowed to settle; a transducer pressing operation in which the transducer is brought into contact with the bolt end at the correct position and with the appropriate pressure; and a measurement acquisition operation in which the measurement value is obtained at the appropriate timing using echo images.

[0011] Furthermore, fastening bolts that are the target of axial force measurement have subtle individual differences in end face shape and thread shape due to the machining manufacturing process, and the bolt end face that the probe contacts is not always a perfectly flat surface, but is almost always an unevenly sloped surface with slight irregularities or inclines.

[0012] To precisely measure the axial force of fastening bolts with individual differences in end face shape, subtle and precise positional adjustments are required during probe pressing and measurement acquisition operations to ensure accurate emission and reception of ultrasonic waves along the length of the bolt from the end face. This involves tilting the probe toward the off-center inclined surface of the bolt end and applying appropriate pressing force to achieve a correct contact position.

[0013] In other words, in the ultrasonic axial force measurement methods of Patent Documents 2 and 3, various exploration operations, including subtle and precise adjustments of the probe's posture when it is brought into contact with the biased inclined surface of the bolt end, naturally become intuitive operations based on certain special skills such as the operator's proficiency and skill level.

[0014] As a result, depending on the skill level of the worker, measurement accuracy could decrease or variations could occur in the measured values, raising doubts about the reliability of axial force measurement.

[0015] Furthermore, when a single fastening object has multiple fastening bolts, all of these complex and specialized exploration operations must be performed multiple times by a single worker for each individual fastening bolt, resulting in an excessive burden on the human resource.

[0016] Furthermore, the ultrasonic axial force measurement method described in Patent Document 4 attempts to reduce the human burden by automating the probe pressing operation and measurement value acquisition operation using an axial force measurement device in which a probe is attached to the tip of a manipulator such as an air cylinder or a robot arm, but the following problems arise.

[0017] In other words, because the manipulator's range of motion is limited, it is not possible to make subtle adjustments to the probe's position to achieve a correct contact position that corresponds to the uneven inclination of the bolt end, which varies from bolt to bolt. Furthermore, there is a risk that the manipulator's driving stress will be transmitted to the probe as an excessive reaction force when the bolt is in contact, potentially causing unintentional damage.

[0018] If an attempt is made to finely adjust the posture of the probe tip at the end of the manipulator so as to correspond to the eccentric inclined surface of the bolt, a special drive mechanism for precisely driving and controlling the manipulator must be installed, which complicates the structure and is disadvantageous in terms of cost.

[0019] The present invention has been made in view of such circumstances, and can reduce the human burden during axial force measurement by automating a part of the exploration operation during ultrasonic axial force measurement, and can accurately incline the probe to the eccentric inclined surface of the bolt end with individual differences and easily automatically adjust it to a correct contact posture in which it contacts with an appropriate pressing force, thereby improving the accuracy of axial force measurement. The present invention provides an axial force measuring device for a fastening bolt and an axial force measuring method for a fastening bolt using the same device.

Means for Solving the Problem

[0020] In order to solve the above problems, the axial force measuring device for a fastening bolt according to the present invention includes: (1) The system comprises a printing device for printing bolt information on the end face of fastening bolts before fastening, a robot arm with an imaging camera attached to its tip, a pre-measurement work area where a bolt-standing container is positioned to house multiple fastening bolts in an upright position with the printed end face protruding upward, a post-measurement work area where the wheel is positioned after the brake disc has been fastened with the fastening bolts, and a monitor unit for displaying various conditions and measurement results, and further, A horizontal mounting base at the tip of the robot arm, and a probe body disposed below the horizontal mounting base for measuring the bolt length from the end face of the fastening bolt by an ultrasonic transmitting and receiving function of And a connecting spring interposed and connected between the horizontal mounting base and the probe body for pressing the probe body against the end face of the fastening bolt probe having And an axial force measuring device configured to measure the axial force of the fastening bolt by a probe at the tip of the robot arm of It is characterized by the above. The printing device, probe, imaging camera, robot arm, and control device electrically connected to the monitor unit, The tip of the robot arm Below the horizontal mounting base To The attached By a probe For mounting brake discs to the wheels of rail vehicles An axial force measuring device for measuring the axial force of a fastening bolt The control device performs a bolt information assignment process, which involves controlling the printing device to print bolt information on the end face of the fastening bolt; controlling the robot arm to read the bolt information printed on the end face of each fastening bolt in the bolt-standing container placed in the pre-measurement work station, transmit it to the control device using the imaging camera, face the probe toward the end face of the bolt coated with the coupling medium, bring the probe into contact with the bolt to achieve a normal contact position, rotate the probe back and forth, wait for a certain period of time after the operation stops, then acquire a measurement value of the fastening bolt with the probe and store the obtained measurement value in the control device; and the robot arm performs a pre-axial force measurement process, which involves controlling the printing device to print the bolt information on the end face of each fastening bolt of the wheel, which has been fastened with the fastening bolts that have undergone the pre-axial force measurement process and is placed in the post-measurement work station, and transmitting it to the control device using the imaging camera. The system can perform the following processes: a post-axial force measurement process, which involves controlling the robot arm to read the image from the imaging camera and transmit the data to the control device; positioning the probe toward the end face of the bolt coated with a coupling medium and bringing the probe into contact with it to achieve a normal contact position; rotating the probe back and forth; waiting for a certain period of time after the operation stops; then acquiring a measurement value of the fastening bolt using the probe and storing the obtained measurement value in the control device; and an appropriate axial force determination process, which involves calculating the axial force based on the difference between the measurement value in the pre-axial force measurement process and the measurement value in the post-axial force measurement process; determining that the fastening bolt is normal if the axial force is within a predetermined appropriate axial force range, while determining that the fastening bolt is abnormal if it deviates from that range; sending a stop signal to the robot arm and an abnormality signal to the monitoring unit to notify the operator of the fastening bolt with an abnormal axial force. It is characterized by being configured.

[0022] Also, in the present invention, The system comprises a printing device for printing bolt information on the end face of fastening bolts before fastening, a robot arm with an imaging camera attached to its tip, a pre-measurement work area where a bolt-standing container is positioned to house multiple fastening bolts in an upright position with the printed end face protruding upward, a post-measurement work area where the wheel is positioned after the brake disc has been fastened with the fastening bolts, and a monitor unit for displaying various conditions and measurement results, and further, A horizontal mounting base at the tip of the robot arm, and a probe body disposed below the horizontal mounting base for measuring the bolt length from the end face of the fastening bolt by an ultrasonic transmitting and receiving function of And a connecting spring interposed and connected between the horizontal mounting base and the probe body for pressing the probe body against the end face of the fastening bolt probe having And a connecting spring interposed and connected between the horizontal mounting base and the probe body for pressing the probe body against the end face of the fastening bolt of And a connecting spring interposed and connected between the horizontal mounting base and the probe body for pressing the probe body against the end face of the fastening bolt The printing device, probe, imaging camera, robot arm, and control device electrically connected to the monitor unit,robot arm tip Below the horizontal mounting base to The attached By the probe For mounting brake discs to the wheels of rail vehicles Axial force measuring device for measuring the axial force of fastening bolts A method for measuring axial force using the following: The control device performs a bolt information assignment process, which involves controlling the printing device to print bolt information on the end face of the fastening bolt; controlling the robot arm to read the bolt information printed on the end face of each fastening bolt in the bolt-standing container placed in the pre-measurement work station, which is then read by the imaging camera and transmitted to the control device; bringing the probe face to the end face of the bolt coated with a coupling medium, bringing the probe into contact with the bolt to achieve a normal contact position; rotating the probe back and forth; waiting for a certain period of time after the operation stops; then acquiring a measurement value of the fastening bolt with the probe and storing the obtained measurement value in the control device; and a pre-axial force measurement process, which involves controlling the robot arm to read the bolt information printed on the end face of each fastening bolt of the wheel, which is fastened with the fastening bolts that have undergone the pre-axial force measurement process and is placed in the post-measurement work station, which is then read by the imaging camera and transmitted to the control device. The following are performed: a post-axial force measurement process in which the robot arm is controlled to read the image using the imaging camera and transmit the result to the control device, the probe is brought into contact with the end face of the bolt coated with a coupling medium and brought into contact with it to achieve a normal contact position, the probe is rotated back and forth, the operation is stopped and the device waits for a certain period of time, and then the probe is used to obtain a measurement value of the fastening bolt and the obtained measurement value is stored in the control device; and an appropriate axial force determination process is performed in which the axial force is calculated based on the difference between the measurement value in the pre-axial force measurement process and the measurement value in the post-axial force measurement process, the fastening bolt is determined to be normal if the axial force is within a predetermined appropriate axial force range, while the fastening bolt is determined to be abnormal if it deviates from the range, a stop signal is sent to the robot arm and an abnormality signal is sent to the monitoring unit to notify the operator of the fastening bolt with an abnormal axial force. The present invention also provides a method for measuring the axial force of fastening bolts, characterized by the following: [Effects of the Invention]

[0023] Axial force measuring device According to the invention relating to this invention, The system comprises a printing device for printing bolt information on the end face of fastening bolts before fastening, a robot arm with an imaging camera attached to its tip, a pre-measurement work area where a bolt-standing container is positioned to house multiple fastening bolts in an upright position with the printed end face protruding upward, a post-measurement work area where the wheel is positioned after the brake disc has been fastened with the fastening bolts, and a monitor unit for displaying various conditions and measurement results, and further, The horizontal mounting base at the tip of the robot arm and the fastening bolts located below the horizontal mounting base, which transmit and receive ultrasonic waves. of Probe body for measuring bolt length from end face probe having The horizontal mounting base and the probe body are interposed and connected, and the probe body is fastened with the fastening bolts. of A connecting spring that presses against the end face, An axial force measuring device comprising a printing device, a probe, an imaging camera, a robot arm, and a control device electrically connected to a monitor unit, wherein the probe mounted below the horizontal mounting base at the tip of the robot arm measures the axial force of fastening bolts for attaching brake discs to the wheels of a rail vehicle, wherein the control device controls the printing device to print bolt information on the end face of the fastening bolt, controls the robot arm to read the bolt information printed on the end face of each fastening bolt in the bolt-standing container placed in the pre-measurement work station and transmit it to the control device using the imaging camera, faces the end face of the bolt coated with a coupling medium and brings the probe into contact with the bolt to achieve a normal contact position, rotates the probe back and forth, waits for a certain period of time after the operation stops, then obtains a measurement value of the fastening bolt using the probe and stores the obtained measurement value in the control device, and performs an axial force pre-measurement process after the fastening bolt has undergone the axial force pre-measurement process The system can perform the following processes: a post-axial force measurement process in which the robot arm controls the imaging camera to read bolt information printed on the end face of each fastening bolt of a wheel that has been fastened to a brake disc and is set in the post-measurement work area, transmits the information to the control device, faces the end face of the bolt coated with a coupling medium and brings the probe into contact with it to achieve a normal contact position, rotates the probe back and forth, waits for a certain period of time after the operation stops, then obtains a measurement value of the fastening bolt with the probe and saves the obtained measurement value to the control device; and an appropriate axial force determination process in which the axial force is calculated based on the difference between the measurement value in the pre-axial force measurement process and the measurement value in the post-axial force measurement process, determines that the fastening bolt is normal if the axial force is within a predetermined appropriate axial force range, determines that the fastening bolt is abnormal if it deviates, sends a stop signal to the robot arm and sends an abnormality signal to the monitor unit for the abnormal fastening bolt to notify the operator of the fastening bolt with an abnormal axial force. As a result of this configuration, it is possible to automate part of the exploration operation when measuring the axial force of fastening bolts, thereby improving the accuracy of axial force measurement and reducing the human burden during measurement.

[0024] In other words, the robotic arm automatically positions the probe body above the fastening bolt to be measured among multiple fastening bolts. Then, during exploration operations such as medium settling and probe pressing, the connecting spring allows the probe body to be positioned correctly to face the bolt end face, which may have individual differences in end face shape, and to be easily and accurately displaced to a correct contact position with the appropriate pressing force.

[0025] Specifically, when the robot arm moves and the probe body at the tip makes pressure contact with the bolt end face, the connecting spring absorbs the excessive pressure from the robot arm and undergoes elastic contraction, causing the probe body at the tip to displace to an inclined position in response to the uneven inclination of the bolt end. This allows the probe body to automatically adjust to a normal contact position where the entire bottom surface of the probe body makes surface contact with the bolt end face, matching the inclination gradient.

[0026] Therefore, the probe can be easily and automatically operated via a robotic arm to match fastening bolts with individual differences in end face shape, and ultrasonic waves can be transmitted and received along the length direction of the fastening bolt from the entire contact bottom surface of the probe body, resulting in precise and highly reliable axial force measurement.

[0027] Furthermore, when the probe body is moved away from the bolt end face to assume a standby position after axial force measurement, the connecting spring extends and returns to its original position, thereby holding the probe body at a certain distance from the horizontal mounting base and maintaining the probe body in a constant horizontal standby position.

[0028] Therefore, since a consistent horizontal waiting position can be reproduced for each new fastening bolt axial force measurement, variations in the axial force measurements obtained for each bolt can be prevented, resulting in stable and repeated axial force measurements.

[0034] Also, Method for measuring the axial force of fastening bolts According to the invention relating to this invention, The system comprises a printing device for printing bolt information on the end face of a fastening bolt before fastening, a robot arm with an imaging camera attached to its tip, a pre-measurement work area where a bolt-standing container is arranged that houses multiple fastening bolts in an upright position with the end face printed with the bolt information protruding upward, a post-measurement work area where a wheel is arranged after the brake disc has been fastened with the fastening bolts, and a monitor unit for displaying various conditions and measurement results. Furthermore, it includes a horizontal mounting base at the tip of the robot arm, and a device disposed below the horizontal mounting base that transmits and receives ultrasonic waves from the end face of the fastening bolt. A method for measuring axial force using an axial force measuring device, comprising: a probe having a probe body for measuring the length of a bolt; a connecting spring interposed and connected between the horizontal mounting base and the probe body to press the probe body against the end face of the fastening bolt; and a control device electrically connected to the printing device, probe, imaging camera, robot arm, and monitor unit, wherein the probe mounted below the horizontal mounting base at the tip of the robot arm measures the axial force of a fastening bolt for attaching a brake disc to the wheel of a rail vehicle, wherein the control device controls the printing device to measure the axial force of the fastening bolt for attaching a brake disc to the wheel of a rail vehicle, the control device controls the printing device to measure the length of the fastening bolt A pre-measurement process for axial force involves: a bolt information assignment process that prints bolt information on the end face of a bolt; and a process that controls the robot arm to read the bolt information printed on the end face of each fastening bolt in the bolt-standing container placed in the pre-measurement work area using the imaging camera and transmit it to the control device; bringing the probe face to face the end face of the bolt coated with a coupling medium, bringing the probe into contact with it to achieve a normal contact position; rotating the probe back and forth; waiting for a certain period of time after the operation stops; then acquiring a measurement value of the fastening bolt using the probe and saving the obtained measurement value to the control device. The post-axial force measurement process involves the robot arm controlling the imaging camera to read bolt information printed on the end face of each fastening bolt of the wheel, which has been fastened with the fastening bolts that have undergone the pre-axial force measurement process and is positioned in the post-measurement work area, and transmitting this information to the control device. The probe is then brought into contact with the end face of the bolt coated with a coupling medium, and the probe is brought into contact with the end face to achieve a normal contact position. The probe is then rotated back and forth, and after the operation stops, the system waits for a certain period of time. After that, the probe is used to obtain a measurement value of the fastening bolt, and the obtained measurement value is stored in the control device.The process involves calculating the axial force based on the difference between the measurement value obtained in the pre-axial force measurement process and the measurement value obtained in the post-axial force measurement process. If the axial force is within a predetermined appropriate axial force range, the fastening bolt is determined to be normal. If it deviates from this range, the fastening bolt is determined to be abnormal. A stop signal is sent to the robot arm, and an abnormality signal for the abnormal fastening bolt is sent to the monitoring unit to notify the operator of the fastening bolt with abnormal axial force. As a result of this decision, the measurement acquisition process is automated to obtain measurement values ​​at the appropriate time, eliminating variations in axial force measurement results. Furthermore, because the determination of appropriate axial force is automated, evaluation and inspection results can be determined immediately, resulting in labor savings and increased efficiency in inspection work. [Brief explanation of the drawing]

[0035] [Figure 1] This is an overall schematic diagram of the fastening bolt axial force measuring device according to the present invention. [Figure 2] This is a side view showing the configuration of the fastening bolt axial force measuring device according to the present invention. [Figure 3] This is a bottom view showing the configuration of the horizontal mounting base at the tip of the robot arm according to the present invention. [Figure 4] These are a plan view and a partially enlarged side view showing the configuration of the hand portion at the tip of the robot arm according to the present invention. [Figure 5] This is a schematic diagram illustrating the attitude displacement of the probe body at the tip of the robot arm according to the present invention. [Figure 6] This is a side view showing the usage state of the bolt-standing container according to the present invention. [Figure 7] These are a plan view and a partially enlarged perspective view showing the configuration of the bolt-standing container according to the present invention. [Figure 8] This is a block diagram showing the electrical configuration of a fastening bolt axial force measuring device according to the present invention. [Figure 9] This is a flowchart of a method for measuring axial force using the fastening bolt axial force measuring device according to the present invention. [Modes for carrying out the invention]

[0036] The gist of the present invention is to provide an axial force measuring device for fastening bolts that fasten fastened members together using a probe capable of measuring bolt length by ultrasonic waves, which is attached to the tip of a robot arm, characterized in that the device comprises a horizontal mounting base at the tip of the robot arm, a probe body disposed below the horizontal mounting base and measuring the bolt length from the end face of the fastening bolt by transmitting and receiving ultrasonic waves, and a connecting spring interposed and connected between the horizontal mounting base and the probe body to press the probe body against the end face of the fastening bolt.

[0037] Furthermore, the connecting spring is characterized in that it is interposed between the disc body to which the probe body is attached and the horizontal mounting base, with the disc facing downwards.

[0038] Furthermore, the connecting spring is characterized in that it is wound around a spring guide rod located between the horizontal mounting base and the disc body.

[0039] Furthermore, it is characterized by being composed of a coupling catalyst that, when applied to the end face of the fastening bolt, allows the probe body to be pressed and fitted to the end face of the fastening bolt with optimal conformity.

[0040] Furthermore, the present invention also provides a method for measuring the axial force of a fastening bolt using the fastening bolt axial force measuring device described in any one of claims 1 to 4, characterized in that, when measuring the axial force of the fastening bolt with the probe, the measured value of the axial force of the fastening bolt before fastening the fastened members together and the measured value of the axial force of the fastening bolt after fastening the fastened members together are compared and calculated, and the appropriateness of the axial force of the fastening bolt is determined based on the difference.

[0041] In the axial force measuring device for fastening bolts and the axial force measuring method using the device according to the present invention, the fastened members to be measured by the fastening bolts are not particularly limited, and may be, for example, the wheels and brake discs of a rail vehicle, the pipes that circulate cooling water in a nuclear power plant or the pipes and joints, or the vehicle frame and seats of a bus vehicle. In other words, the axial force measuring device and the axial force measuring method using the device according to the present invention can measure the axial force as an evaluation of the fastening force of fastening bolts that fasten fastened members together.

[0042] Furthermore, it goes without saying that the fastening bolts F targeted for axial force measurement in this device and the axial force measurement method using this device may be single or multiple. In other words, as described above, the axial force measuring device and the axial force measuring method using the present invention are configured to automate a part of the exploration operation during ultrasonic axial force measurement using a robotic arm with a probe attached to its tip. Therefore, even when a single fastening structure fastens multiple fastening bolts together, a certain level of measurement accuracy can be maintained, and the axial force measurement of each of the multiple fastening bolts can be stably performed.

[0043] Furthermore, the fastening bolt end faces that the probe body contacts refer to both longitudinal ends of the fastening bolt, and this device and the axial force measurement method using this device also include embodiments in which the probe body is brought into contact with the tip face of the threaded portion or the head end face of the fastening bolt for measurement.

[0044] Furthermore, while this device primarily serves the function of measuring the axial force of fastening bolts, it naturally also performs a flaw detection function and can be used for ultrasonic flaw detection to check for any accidental cracks or other damage inside the threaded portion or head of the bolt.

[0045] In other words, the axial force measuring device according to the present invention includes an ultrasonic flaw detection device that is also used for ultrasonic flaw detection or as an ultrasonic flaw detection device alone.

[0046] The following describes in detail, with reference to drawings, an embodiment of the fastening bolt axial force measuring device and the axial force measuring method using the device according to the present invention. Figure 1 is an overall schematic diagram of the fastening bolt axial force measuring device, Figure 2 is a side view showing the configuration of the fastening bolt axial force measuring device, Figure 3 is a bottom view showing the configuration of the horizontal mounting base at the tip of the robot arm, Figure 4(a) is a plan view of the disc body in the hand portion at the tip of the robot arm, Figure 4(b) is an enlarged side view showing the configuration of the hand portion at the tip of the robot arm, Figures 5(a) and 5(b) are schematic side views showing the attitude displacement state of the probe body at the tip of the robot arm, Figure 5(c) is a schematic side view showing the attitude displacement state of the disc body, spring guide rod and connecting spring at the tip of the robot arm, Figure 6 is a side view showing the usage state of the bolt erection container, Figure 7 is a plan view, partially enlarged plan view and perspective view showing the configuration of the bolt erection container, Figure 8 is a block diagram showing the electrical configuration of the fastening bolt axial force measuring device, and Figure 9 is a flowchart of the axial force measuring method using the fastening bolt axial force measuring device.

[0047] <1. Overview of the fastening bolt axial force measuring device> Device A is configured to compare and calculate the axial force of the fastening bolts F before the brake disc D is attached to the wheel W of a rail vehicle (hereinafter simply referred to as "pre-axial force measurement") and the axial force of the fastening bolts F after the brake disc D is attached to the wheel W (hereinafter simply referred to as "post-axial force measurement"), and to determine the appropriateness of the axial force of the fastening bolts F based on the difference between the two measurements.

[0048] In general terms, as shown in Figure 1, the device A comprises a robot arm 1 that serves as the center of exploration operations and is equipped with a probe 2 capable of measuring bolt length using ultrasound at its tip; a control device 6 that controls the operation of the robot arm 1 and processes the measured bolt length values ​​obtained by the probe 2; a bolt upright container 7 used during pre-axial force measurement to neatly store and arrange multiple fastening bolts F in an upright position before fastening; a printing device 8 for printing bolt information to identify each of the multiple upright fastening bolts F; and a conveyor C used during post-axial force measurement to transport the wheel W, to which the brake disc D has been fastened with multiple fastening bolts F, to the position of the robot arm 1.

[0049] The printing device 8 is not particularly limited as long as it is capable of printing bolt information that allows multiple bolts to be identified from one another onto the tip surface F1 of each fastening bolt F that has been raised by the bolt upright container 7.

[0050] The printing device 8 uses a quick-drying ink spraying method from the viewpoint of reading accuracy by the imaging camera 310, and the bolt information printed on the fastening bolt end face F1 may be a string of characters combining letters and numbers.

[0051] The robot arm 1 is configured as a so-called 6-axis vertical articulated arm, and the axial force measuring device A is configured by attaching a probe 2 for measuring axial force to the hand portion at the tip of the robot arm 1.

[0052] Specifically, as shown in Figure 2, the robot arm 1 consists of a base portion 10 held at a constant height, a lower pivot portion 11 which is L-shaped in side view and rotates horizontally on the base portion 10 around a pivot axis 11a, a lower arm portion 12 which swings up and down on the lower arm axis 12a at the L-shaped tip of the lower pivot portion 11, an intermediate arm portion 13 which swings up and down on the intermediate arm axis 13a at the tip of the lower arm portion 12, an upper arm portion 14 which rotates laterally on the upper pivot axis 14a on the tip surface of the intermediate arm portion 13, a wrist portion 15 which swings up and down on the wrist axis 15a at the tip of the upper arm portion 14, and a hand mounting plate 16 which rotates laterally on the hand pivot axis 16a on the tip surface of the wrist portion 15.

[0053] Furthermore, as shown in Figure 1, a measurement work position 9 is provided near the robot arm 1 to set a fixed position for the bolt end face F1, where the relative distance from the robot arm 1 to the bolt end face F1 is constant within the arm reach range of the robot arm 1 when the fastening bolt F is installed.

[0054] Specifically, the measurement work placement section 9 consists of a pre-measurement work placement section 90 for setting up a bolt-standing container 7, which stores fastening bolts F in an upright position, in a fixed configuration within the arm reach range centered on the robot arm 1 during pre-axial force measurement, and a post-measurement work placement section 91 for setting up a fastened object, which is constructed by fastening fastened members together with fastening bolts F, in a fixed configuration on the transport conveyor C during post-axial force measurement.

[0055] As a result, the position of the fastening bolts F in the bolt erection container 7 and fastened objects is fixed within a certain area of ​​the measurement work stationary section 9, the distance between the bolt end face F1 and the robot arm 1 becomes constant, and the control of the positioning movement of the robot arm 1 becomes easier.

[0056] Furthermore, the post-measurement work fixing section 91 supports and fixes the lower end of the bolt, which is exposed at the lower end of the fastened object, and the central part of the fastened object from below, thereby enabling the bolt end face F1 to be fixed within a certain area of ​​the post-measurement work fixing section 91.

[0057] Furthermore, if there are multiple fastening bolts F to be measured for axial force within each installation section 90, 91 (bolt erection container 7 or fastening object), multiple fixing positions are set according to the relative distance between each bolt end face F1 and the robot arm 1.

[0058] Furthermore, the pre-measurement work fixing section 90 and the post-measurement work fixing section 91 only need to be configured such that, in a plan view, the bolt end face F1 is exposed and fixed at a certain distance from the position of the robot arm 1, and they may be provided in the same location.

[0059] Thus, as shown in Figure 1, this device A is equipped with a probe 2 capable of measuring bolt length using ultrasound at the tip of a robot arm 1, which corresponds to the hand portion. The robot arm 1 then sequentially applies the probe 2 to the end faces F1 of each of the multiple fastening bolts F used to attach the brake disc D to the wheel W, and attempts to measure the axial force.

[0060] <2. Specific Configuration of the Fastening Bolt Axial Force Measuring Device> As shown in Figures 2 and 4, the device A consists of a horizontal mounting base 3 attached to the tip of a robot arm 1, a probe body 20 positioned below the horizontal mounting base 3 and measuring the bolt length from the end face of the fastening bolt using ultrasonic wave transmission and reception functions, and a connecting spring 4 interposed and connected between the horizontal mounting base 3 and the probe body 20 to press the probe body 20 against the end face F1 of the fastening bolt.

[0061] As shown in Figures 2 and 3, the horizontal mounting base 3 is rectangular in shape and is rotatably mounted parallel to the tip surface of the robot arm 1 at its tip. Below it, the probe 2 and imaging camera 310 necessary for axial force measurement are mounted adjacent to each other.

[0062] Specifically, the horizontal mounting base 3 is configured as a probe mounting section 30 in which the front half of the rectangular longitudinal section is fixed in surface contact with the hand mounting plate 16 at the tip of the robot arm 1 on the top surface, and the probe 2 is suspended from the bottom surface via a connecting spring 4. The rear half of the rectangular longitudinal section that extends laterally from the tip of the robot arm 1 is configured as a camera mounting section 31 in which the imaging camera 310 is suspended from the bottom surface.

[0063] As shown in Figures 2 and 3, the imaging camera 310 is mounted vertically on the bottom surface of the camera mounting section 31 of the horizontal mounting base 3, with its lens surface 310a facing downwards, so that it has a field of view that allows it to capture bolt information printed on the end face F1 of the fastening bolt F by the printing device 8.

[0064] The connecting springs 4, 4', and 4'' are so-called compression coil springs, as shown in Figures 2, 4(a), and 4(b), and are arranged point-symmetrically (on a virtual ring centered on the axis 20a) around the axis 20a of the probe body 20 in a plan view.

[0065] Specifically, as shown in Figures 2, 4', and 4(b), the connecting springs 4, 4', and 4'' are arranged in multiple positions between the disc body 5, on which the probe body 20 is mounted facing downwards, and the horizontal mounting base 3. Each spring is connected and fixed to the bottom surface of the horizontal mounting base 3 at its upper end and to the top surface of the disc body 5 at its lower end. Note that the connecting spring 4 may be a single spring, provided that it is point-symmetrical with respect to the axis 20a of the probe body 20.

[0066] As shown in Figures 3 to 4(b), on the bottom surface of the probe mounting section 30 of the horizontal mounting base 3, multiple (3) connecting springs 4, 4', and 4'' are suspended at regular intervals around the periphery of a virtual circle 30C. A disc-shaped body 5 identical to the virtual circle 30C is attached in phase to the lower end of each of these springs, and a probe 2 is suspended from the center of the bottom surface of the disc-shaped body 5.

[0067] Furthermore, the connecting springs 4, 4', and 4'' are each wrapped around a plurality (3) of spring guide rods 40, 40', and 40'' located between the horizontal mounting base 3 and the disc body 5, as shown in Figures 2, 4(a), and 4(b).

[0068] As shown in Figures 2, 4(a), and 4(b), the spring guide rods 40, 40', and 40'' each have their upper ends connected and fixed to the probe mounting section 30 of the horizontal mounting base 3, while their hanging lower ends are slidably inserted into a plurality (3) of notched holes 50, 50', and 50'' formed at regular intervals in a roughly arc shape on the periphery of the disc body 5.

[0069] In other words, the notches 50, 50', and 50'' of the disc body 5 are formed to accommodate the insertion of the spring guide rods 40, 40', and 40'' that hang down from the virtual circle 30C of the horizontal mounting base 3, as shown in Figures 4(a) and 4(b).

[0070] Each of the notches 50, 50', and 50'' is formed with an outer diameter slightly larger than the outer diameter of the spring guide rod 40, and as shown in Figures 4(a), 5(b), and 5(c), a certain clearance space 51, 51', and 51'' is provided between the outer circumference of the spring guide rod 40 and the disc body 5, which receives an upward reaction force from the fastening bolt end face F1, is in an inclined position.

[0071] In particular, the notches 50a, 50a', and 50a'' at the circumferential edge of the disc body 5, which have notches 50, 50', and 50'', function as clearance openings that allow the spring guide rod 40 to move outward when the disc body 5 is in an inclined position, and are connected to the clearance spaces 51, 51', and 51''.

[0072] The connecting springs 4, 4', and 4'' are loosely fitted between the horizontal mounting base 3 and the disc body 5, with their upper end faces in contact with the bottom surface of the horizontal mounting base 3 at the outer circumference of the upper end of the spring guide rods 40, 40', and 40'', and their lower end faces in contact with the top surface of the disc body 5 at the outer circumference of the notched holes 50, 50', and 50''.

[0073] These spring guide rods 4, 4', and 4'' allow the range of contraction elastic deformation of the connecting springs 4, 4', and 4'' and the range of tilting displacement of the disc body 5 at the arm tip to be restricted to a certain range, thereby stabilizing the positive contact posture of the probe body 20 at the arm tip.

[0074] Furthermore, when the probe body 20 is moved away from the bolt end face F1 after axial force measurement, the connecting springs 4, 4', and 4'' can be extended and returned along the spring guide rods 4, 4', and 4'', thereby further stabilizing the horizontal standby position of the probe body 20 by maintaining a constant distance between the horizontal mounting base 3 and the disc body 5 in a plane-parallel position.

[0075] Furthermore, as shown in Figures 2 and 4(b), ring-shaped flanges 41, 41', and 41'' are formed to protrude outward from the outer circumference of the lower ends of the spring guide rods 40, 40', and 40''. These flanges contact the outer circumference of the notches 50, 50', and 50'' from the bottom side when the disc body 5 moves downward away from the horizontal mounting base 3 as the connecting springs 4, 4', and 4'' between the horizontal mounting base 3 and the disc body 5 return to their spring elastic state.

[0076] This prevents the spring guide rods 40, 40', and 40'' from unintentionally detaching from the notches 50, 50', and 50'' of the disc body 5, thereby maintaining the disc body 5 at a constant distance from the horizontal mounting base 3 and more stably reproducing the horizontal standby position of the probe 2.

[0077] The probe 2 is a so-called single-element transducer with a multi-stage cylindrical shape of varying sizes, and as shown in Figures 2, 4(a), and 4(b), it consists of a medium-sized cylindrical fixing part 21 attached to the center of the bottom surface of the disc body 5, a large cylindrical connector part 22 below the fixing part 21 into which the end of the connecting cord connected to the control device 6 can be inserted, and a small cylindrical probe body 20 below the connector part 22 in which the ultrasonic transmitting part and the receiving part are integrated.

[0078] As shown in Figures 2 and 4(b), the circular bottom surface of the probe body 20 is formed as a contact flat surface 20b that abuts against the fastening bolt end face F1, with an area less than or equal to the fastening bolt end face F1, and is configured to emit ultrasonic waves and receive reflected waves.

[0079] In Figures 2, 4(a), and 4(b), reference numeral 210 denotes a fixing pin hole that penetrates the fixing part 21 and the disc body 5, reference numeral 221 denotes a connection cord that connects to the control device 6, reference numeral 220 denotes a connector insertion port into which the end of the connection cord is inserted, and reference numeral 200 denotes a ring-shaped magnet fitted onto the tip of the probe body 20 to improve contact with the fastening bolt end face F1.

[0080] Furthermore, as shown in Figure 2, the probe body 20 is vertically mounted from the disc body 5 such that its axis 20a is aligned with the axis of the tip of the robot arm 1 (the rotation axis of the horizontal mounting base 3, i.e., the hand rotation axis 16a of the hand mounting plate 16) and the center of the disc body 5.

[0081] In other words, as shown in Figure 4(a), the probe body 20 has its axis 20a aligned with the centroid (center 5a of the disc body 5) of a virtual polygon formed by multiple spring guide rods 40, 40', 40'' (multiple connecting springs 4, 4', 4'') in a plan view.

[0082] As a result, when the robot arm 1 descends and the probe body 20 at its tip makes contact with the end face F1 of the fastening bolt below, the upward reaction force from the fastening bolt end face F1 is distributed and transmitted from the probe 2 to the connecting springs 4, 4', and 4'' around the center 5a of the disc body 5.

[0083] Specifically, as shown in Figure 5(a), the probe 2, which is in a horizontal standby position at the tip of the robot arm 1, is positioned above the fastening bolt F to be measured by the movement of the robot arm 1, with its axis 20a coaxial with the bolt axis and its contact flat surface 20b facing the fastening bolt F.

[0084] Furthermore, the positioning operation of the probe 2 by the robot arm 1 does not require the axis 20a of the probe 2 to be coaxial with the bolt axis, as long as the contact flat surface 20b of the probe body 20 in the horizontal standby position faces the fastening bolt end face F1 of the fastening bolt F and is within the diameter range of the threaded portion of the fastening bolt F.

[0085] Next, the probe 2 is lowered vertically via the robot arm 1, and the contact flat surface 20b of the probe body 20 is pressed against the bolt end face F1 to ensure close contact.

[0086] In this case, even if the fastening bolt end face F1 is an off-center inclined surface, as shown in Figure 5(a), the contact portion between the probe body 20 and the fastening bolt end face F1 is such that the peripheral edge eccentric from the axis 20a of the probe body 20 (the center 5a of the disc body 5) becomes the contact point T, and the contraction rate of each connecting spring 4, 4, 4'' changes according to the distance between this eccentric contact point T and each connecting spring 4, 4, 4''.

[0087] In other words, the pressing reaction force transmitted from the contact pivot point T of the probe 2 to each connecting spring 4, 4', and 4'' via the disc body 5 acts more strongly closer to the contact pivot point T and weaker further away from the contact pivot point T, as shown in Figure 5(b).

[0088] As a result, as shown in Figures 5(b) and 5(c), the connecting spring 4'' near the contact pivot point T undergoes strong contraction deformation along the spring guide rod 40'', shortening the distance between the horizontal mounting base 3 and the disc body 5, causing the disc body 5 to tilt steeply upward, and the spring guide rod 40'' to be exposed for a long distance below the notch hole 50''.

[0089] Furthermore, the connecting spring 4, which is far from the contact pivot point T, undergoes slight contraction deformation along the spring guide rod 40, maintaining a longer distance between the horizontal mounting base 3 and the disc body 5, while the disc body 5 tilts upward at a gentle slope, and the spring guide rod 40'' is briefly exposed below the notched hole 50''.

[0090] As a result, as shown in Figure 5(b), the disc body 5 is displaced to an inclined position relative to the horizontal mounting base 3 in a side view, and accordingly, the probe body 20, which is integrated with the disc body 5, is automatically adjusted to follow the inclined displacement state in which the contact flat surface 20b faces the inclined slope of the biased inclined surface F1 of the fastening bolt F, i.e., to the normal contact position.

[0091] In this case, each connecting spring 4, 4'4'' acts as a shock absorber to absorb excessive pressing force from the robot arm 1, undergoing contraction and elastic deformation, thus preventing the probe 2 from being unintentionally damaged.

[0092] In this way, the device A is configured to automatically adjust to a correct contact position in which the probe 2 is precisely angled and facing the biased inclined surface F1 of the end of the fastening bolt F, which has individual differences, and makes contact with the appropriate pressing force.

[0093] In another configuration, if there is only one connecting spring 4 and a corresponding spring guide rod 4, the correct contact position of the probe body 20 can be achieved by arranging the axes of each on the same axis as the central axis 16a of the robot arm 1 and the axis 20a of the probe body 20.

[0094] In other words, regardless of the number or size of the connecting springs 4, what is important for this device A is that the connecting springs 4 interposed between the horizontal mounting base 3 at the tip of the robot arm 1 and the probe body 20 are arranged point-symmetrically around the axis 20a of the probe body 20, so that they undergo contraction elastic deformation with a contraction rate corresponding to the distribution of the pressing reaction force received from the biased inclined surface F1 of the fastening bolt F via the probe body 20.

[0095] Furthermore, when the robot arm 1 moves the probe body 20 away from the bolt end face F1 to a standby position after axial force measurement, the connecting springs 4, 4', and 4'' extend and return to their original position while being guided by the spring guide rods 40, 40', and 40'' that hang vertically from the horizontal mounting base 3. Thus, the probe body 20 can be held at a constant distance from the horizontal mounting base 3, keeping the probe body 20 in a constant standby position.

[0096] Therefore, for each subsequent axial force measurement of a new fastening bolt F, the probe 2 can be kept in a constant standby position, preventing variations in the axial force measurements obtained for each bolt and enabling stable and continuous axial force measurement.

[0097] Furthermore, during axial force measurement, a coupling medium is used, which is applied to the end face F1 of the fastening bolt to press and fit the probe body 20 to the end face F1 of the fastening bolt with optimal conformity. Such a coupling medium is not particularly limited as long as it is non-corrosive, soft, and moist, and maintains the ability to transmit and receive ultrasonic waves, such as glycerin paste.

[0098] The application of the coupling medium to the end face F1 of the fastening bolt is basically performed manually by an operator as preparation before axial force measurement. Device A is configured to automatically perform a medium-adhering operation to allow the applied coupling medium to adhere to the end face F1 of the fastening bolt while the probe body 20 is in contact with the end face F1 of the fastening bolt.

[0099] In other words, the device A is configured to perform a settling operation by rotating the horizontal mounting base 3 together with the probe body 20 at the tip of the robot arm 1, as shown in Figure 5(b), thereby causing the contact flat surface 20b of the probe body 20 to slide against the end face F1 of the fastening bolt, spreading and settling the contact catalyst. The horizontal mounting base 3 rotates integrally with the hand mounting plate 16 around the hand pivot axis 16a shown in Figure 2.

[0100] This allows the coupling medium to conform to the inclined irregularities that occur on the bolt end face F1 during the manufacturing process, completely filling the gap between the fastening bolt end face F1 and the probe body 20, thereby improving the transmission of ultrasonic waves.

[0101] Furthermore, the bolt erection container 7 used for pre-measurement of axial force, as shown in Figure 6, is a hollow rectangular box shape and consists of a rectangular bottom plate 70 and a U-shaped cover body 71 that is detachably erected on both ends of the bottom plate 70 to form a certain internal space.

[0102] Multiple bolt head fitting recesses 72 are formed at regular intervals on the inner bottom surface 70a of the bottom plate 70, for fitting the bolt heads and keeping the fastening bolts F upright.

[0103] Furthermore, as shown in Figures 6 and 7, multiple bolt tip insertion holes 73 are formed at regular intervals through the top surface 71a of the cover body 71, allowing fastening bolts F, which are erected in accordance with the bolt head fitting recesses 72 formed in the inner bottom surface 70a, to be inserted with their bolt tips protruding upward.

[0104] Furthermore, a bolt positioning bush 74 is provided on the outer periphery of the bolt tip insertion hole 73 to insert the bolt tip and determine the upright position of the fastening bolt. In Figures 6 and 7, reference numeral 75 denotes a bolt retaining plate that holds down the bottom edge of the fastening bolt head fitted into the bolt head fitting recess 72 to prevent the upright fastening bolt F from lifting up.

[0105] With the bolt-standing container 7 configured in this way, each fastening bolt F is stored and arranged in an orderly manner, with the bolt tip portion inserted through the bolt tip insertion hole 73 exposed above the top surface 71a, thus maintaining a stable upright position.

[0106] Therefore, the printing device 8 can perform bolt information assignment operations to print bolt information on the bolt end face F1 of each fastening bolt F, and the axis 20a of the probe body 20 at the tip of the robot arm 1 can be positioned on the bolt axis to stably perform exploration operations by the robot arm 1 and probe 2 during pre-measurement of axial force.

[0107] <3. Electrical configuration of fastening bolt axial force measuring device> Next, the electrical configuration of the fastening bolt axial force measuring device will be described. As shown in Figure 8, this device A is configured to perform the fastening bolt axial force measuring method, and includes a control device 6 for controlling the operation of various functional members, which is equipped with various information necessary for exploration operation and axial force calculation processing.

[0108] The control device 6 performs the functions of a programmable logic controller (PLC) for controlling the operation of the robot arm 1, an ultrasonic axial force meter for calculating ultrasonic intensity and axial force from the probe 2, and a management PC for saving and managing axial force information for each fastening bolt F.

[0109] The control device 6 is electrically connected to a printing device 8 that prints bolt information on the end face F1 of the fastening bolt, a robot arm 1, a probe 2 at the tip of the robot arm 1, an imaging camera 310 at the tip of the robot arm 1, an input unit 60 for inputting and setting the operating conditions and appropriate range of axial force of the device, and a monitor unit 61 that displays various conditions and measurement results.

[0110] The input unit 60 is not particularly limited as long as it allows the operator to input various types of information; for example, it may be a keyboard and mouse, or a touch panel that can be operated on the monitor unit.

[0111] The monitor unit 61 displays bolt information obtained from the imaging camera 310, operating settings set in the input unit 60, the operating status of the robot arm 1, and the axial force determination result indicating whether the fastening bolts F measured by the probe 2 are within the appropriate axial force range.

[0112] The control unit 6 consists of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and flash memory.

[0113] The ROM stores various programs that allow the CPU to synchronize and link each functional component to perform axial force measurement and calculation processing. These programs include: the swing and rotation operating conditions of the robot arm 1; bolt end face position information of the measurement work station 9, which enables the arm to accurately position the probe body 20 at the tip of the arm to approximately directly above the bolt end face F1 during axial force measurement; medium settling conditions for performing a medium settling rotation operation while maintaining a positive contact posture with the probe body 20 pressed against the bolt end face F1; transport operating conditions of the transport conveyor C; shooting conditions of the imaging camera 310; measurement value acquisition conditions such as the waiting time to acquire ultrasonic waveform data at an appropriate timing when the probe 2 is in contact with the bolt end face; and calculation information necessary for the axial force meter function.

[0114] Here, the bolt end face position information of the measurement work stationary unit 9 refers to information indicating the position of the bolt end face F1 which is fixed at a certain location in the measurement work stationary unit 9.

[0115] Specifically, the pre-measurement bolt end face position information indicates the position of the bolt end face F1 of the fastening bolt F fixed to the bolt upright container 7 when the bolt upright container 7 is fixed to the pre-measurement work fixed position 90, and the post-measurement bolt end face position information indicates the position of the bolt end face F1 of the fastening bolt F fastened to the fastening object when the fastening object is fixed to the fastening object.

[0116] By pre-programming this bolt end face position information into the control device 6, the robot arm 1 can use this information to accurately position the probe body 20 at the tip of the robot arm 1 to approximately directly above the bolt end face F1, thereby realizing arm motion control.

[0117] Furthermore, the RAM functions as a storage area that temporarily stores various information programs when the CPU executes a program, such as bolt information managed by the printing device 8, bolt information and position information of each fastening bolt F transmitted from the imaging camera 310, and operation setting information transmitted from the input unit 60.

[0118] With the control device 6 configured in this way, the operator can significantly reduce the human burden required for measurement by simply inputting various settings via the input unit 60 to operate the robot arm 1 and measure the axial force of the fastening bolt F.

[0119] <4. Workflow for measuring fastening bolt axial force> Next, we will explain the workflow for measuring the axial force of fastening bolts using this device A. This axial force measurement method basically involves comparing the measured value of the axial force of fastening bolts F of probe 2 using this device A with the measured value of the axial force of fastening bolts F before the brake disc D is attached to the wheel W, and the measured value of the axial force of fastening bolts F after the brake disc D is attached to the wheel W, and determining the appropriateness of the axial force of fastening bolts F based on the difference.

[0120] In other words, as shown in Figure 9, this axial force measurement method consists of five processes: a bolt information application step P1 in which bolt information is printed onto each fastening bolt F to be measured using a printing device 8 as preparation for axial force measurement; a pre-axial force measurement step P2 in which the axial force measurement value of the fastening bolt F is obtained before fastening the members; a bolt fastening step P3 in which the members are fastened together with the fastening bolt F after the pre-axial force measurement step P2; a post-axial force measurement step P4 in which the axial force measurement value of the fastening bolt F is obtained after fastening the members; and an axial force determination step P5 in which the axial force of the fastening bolt F is calculated from the measurement values ​​obtained in the pre-axial force measurement step P2 and the post-axial force measurement step P4 and the axial force is determined to determine whether the axial force is within the appropriate axial force range.

[0121] (P1: Bolt information assignment process) Process P1 is a measurement preparation process performed before measuring the axial force of multiple fastening bolts F in order to accurately measure the axial force of the fastening bolts, and consists of the following two work steps: (1) bolt information printing step S1-1 and (2) bolt container installation step S1-2.

[0122] (1) Bolt information printing step S1-1 This step involves printing bolt information on the bolt end face F1 of the fastening bolts F. A printing device 8, which is linked to the control device 6, assigns a mutually identifiable string to each fastening bolt F and prints it.

[0123] (2) Bolt container installation step S1-2 This step involves storing and installing multiple fastening bolts F to be measured in an upright position within the bolt upright container 7. As described above, the multiple fastening bolts F are stably held in an upright position with their bolt heads fitted into the bolt head fitting recesses 72 within the bolt upright container 7 and their bolt tips protruding upward from the top surface 71a, making it easier to perform the exploration operation in pre-axial force measurement.

[0124] Steps S1-1 and S1-2 are interchangeable. For example, bolt information may be printed on each of the multiple bolt end faces F1 exposed at the top surface 71a via the bolt container installation step S1-2 using the printing device 8 as the bolt information printing step S1-1.

[0125] (P2: Axial force pre-measurement process P2) Process P2 is a process in which various exploration operations centered on the probe 2, such as the medium settling operation, probe pressing operation, and measurement value acquisition operation in axial force measurement, are performed and the measurement values ​​are saved in the control device 6. It consists of six work steps: (1) bolt information reading step S2-1, (2) coupling medium application step S2-2, (3) probe pressing step S2-3, (4) medium settling step S2-4, (5) measurement value acquisition step S2-5, and (6) data saving step S2-6.

[0126] (1) Bolt information reading step S2-1 This step involves the control device 6 positioning the imaging camera 310 at the tip of the robot arm 1 above the fastening bolts F to be measured, reading the bolt information printed on each bolt end face F1 with the imaging camera 310, and transmitting and recording that information to the control device 6.

[0127] The recorded bolt information is referenced and used when allocating data such as measured values ​​and axial force of the fastening bolts F in the data storage step S2-6, the post-axial force measurement step P4, and the appropriate axial force determination step P5, which will be described later.

[0128] (2) Coupling medium application step S2-2 This step involves applying a coupling medium to the end face F1 of each bolt. Basically, this is done by an operator applying an appropriate amount of glycerin paste, which serves as the coupling medium, to the end face F1 of each fastening bolt F.

[0129] (3) Probe pressing step S2-3 This step involves moving the probe body 20 from its standby position to a proper position facing the bolt end face F1, and bringing the probe body into contact with the bolt with the appropriate pressing force to a forward contact position. Specifically, the control device 6 positions the probe 2 at the tip of the robot arm 1 above the fastening bolt F to be measured, with the axis 20a of the probe 2 in the standby position coaxial with the bolt axis.

[0130] Subsequently, the probe 2 is lowered vertically via the robot arm 1, and the contact flat surface 20b of the probe body 20 is pressed against the bolt end face F1 to ensure close contact. The positioning operation of the tip of the robot arm 1 on the bolt end face F1 in this step and the bolt information reading step S2-1 is automatically controlled based on the pre-measured bolt end face position information of the pre-measured work position 90 recorded in the control device 6, by installing the bolt erection container 7 in the pre-measured work position 90.

[0131] In this case, even if the fastening bolt end face F1 is an off-center inclined surface, as described above, the connecting springs 4, 4', and 4'' interposed between the horizontal mounting base 3 at the tip of the robot arm 1 and the probe body 20 allow the probe body 20 at the tip to be tilted, so that the contact flat surface 20b can be brought into close contact with the off-center inclined surface.

[0132] (4) Step S2-4 for medium acclimation This step involves rotating the probe body 20 in a forward contact position back and forth to spread and settle the coupling medium between the contact flat surface 20b of the probe 2 and the fastening bolt end face F1 onto the fastening bolt end face F1. This rotational movement of the probe body 20 to settle the medium fills the space between the probe body 20 and the fastening bolt end face F1 with the coupling medium, improving the ultrasonic transmission of the probe body 20.

[0133] (5) Step S2-5 for obtaining measurement values This step involves the control device 6 waiting for a certain period of time after the medium acclimation step S2-4 and then acquiring the measurement value. Specifically, after the control device 6 stops the rotational movement of the probe body 20 to acclimate the medium, the probe body 20 is left stationary in the forward contact position for a certain waiting period (for example, about 2 to 10 seconds) for the coupling medium to settle and the ultrasonic waves to stabilize, and the measurement value is acquired when this waiting period has elapsed.

[0134] This makes it possible to obtain measurement values ​​at the optimal timing when the ultrasonic waves transmitted and received by the probe body 20 have settled down, thus reducing the likelihood of variations in measurement values ​​at each fastening bolt F.

[0135] (6) Data saving step S2-6 This step involves storing the measured values ​​obtained in the measurement value acquisition step S2-5 in the control device 6. Specifically, for each fastening bolt F based on the bolt information, the measured values ​​of the pre-axial force measurement are assigned and stored.

[0136] (P3: Bolt fastening process P3) This process involves fastening the brake disc D to the wheel W using fastening bolts F that have undergone the axial force pre-measurement process P2. The bolts are tightened by screwing and rotating nuts such as nut runners with a constant torque. Multiple fastening bolts (12 in total) are used for each wheel W.

[0137] (P4: Post-axial force measurement process P4) In this process, the post-axial force measurement process S4 is a process for obtaining measured values ​​of the axial force of the fastening bolts F after the members have been fastened. For the fastening bolts F that have been fastened to the wheels W that have been transported by the conveyor C after the bolt fastening process P3, various exploration operations centered on the probe 2 are performed on the fastening bolt end face F1, such as the medium settling operation, probe pressing operation, and measurement value acquisition operation in the axial force measurement.

[0138] In other words, this process basically consists of the same six work steps as the pre-axial force measurement process P2: (1) bolt information reading step S4-1, (2) coupling medium application step S4-2, (3) probe pressing step S4-3, (4) medium settling step S4-4, (5) measurement value acquisition step S4-5, and (6) data storage step S4-6.

[0139] Furthermore, the positioning operation of the tip of the robot arm 1 on the bolt end face F1 in the bolt information reading step S4-1 and the probe pressing step S4-3 is automatically controlled based on the post-measurement bolt end face position information of the post-measurement work positioning unit 91 recorded in the control device 6 by placing the fastened object in the post-measurement work positioning unit 91, as described above.

[0140] Furthermore, in the data storage step S4-6, the control device 6 queries the bolt information of the fastening bolt F whose pre-axial force measurement value was measured in the pre-axial force measurement step P2, and records the post-axial force measurement value on the fastening bolt F that matches this information.

[0141] (P5: Process for determining appropriate axial force P5) This process involves calculating the bolt elongation from the difference between the measured values ​​obtained in the pre-axial force measurement process P2 and the post-axial force measurement process P4, calculating the axial force from the calculated value, and further determining whether the axial force is within the appropriate range pre-set in the control device 6 from the input unit 60.

[0142] In other words, the control device 6 automatically calculates the axial force by multiplying the difference between the pre-axial force measurement value and the pre-axial force measurement value, which are measured and recorded based on the bolt information assigned to each fastening bolt F, by an axial force conversion constant. If the calculated axial force of the fastening bolt F is within the appropriate axial force range, the fastening bolt F is judged to be normal; if it deviates from the appropriate axial force range, the fastening bolt F is judged to be abnormal.

[0143] The axial force determination results from this process are ultimately reflected in the monitoring unit 61. That is, if there are multiple fastening bolts F that fasten members W and D together in a single fastening device, and the axial force of even one of the fastening bolts F is not within the appropriate range, the control device 6 sends a stop signal to the robot arm 1 and also sends an abnormality signal of the abnormal fastening bolt F to the monitoring unit 61.

[0144] Upon receiving the stop signal, the robot arm 1 returns to a waiting area that does not interfere with the wheel W and stops. The monitor unit 61, upon receiving the abnormal signal, notifies the operator of the fastening bolt F with abnormal axial force.

[0145] In this case, the worker removes the faulty fastening bolt F from the wheel W and replaces it with another fastening bolt F measured in the pre-axial force measurement process P2, then performs the tightening work. The wheel W, with the newly replaced fastening bolt F, is then subjected again to the post-axial force measurement process P4 and the appropriate axial force determination process P5.

[0146] Ultimately, if there are multiple fastening bolts F that fasten together the fastened members W and D in a single fastening device, and the axial force of all the fastening bolts F is within the appropriate range, then the fastening between the fastened members, such as "the wheel W and the brake disc D are fastened together with high axial force by multiple fastening bolts F," can be guaranteed, and the robustness and reliability of the fastening device will meet the requirements.

[0147] As described above, the present invention provides an axial force measuring device for fastening bolts that fasten fastened members together using a probe that is attached to the tip of a robot arm and capable of measuring bolt length using ultrasound, comprising: a horizontal mounting base at the tip of the robot arm; a probe body disposed below the horizontal mounting base and measuring the bolt length from the end face of the fastening bolt by transmitting and receiving ultrasound; and a connecting spring interposed and connected between the horizontal mounting base and the probe body to press the probe body against the end face of the fastening bolt. As a result, a part of the exploration operation during axial force measurement of fastening bolts can be automated, improving the accuracy of axial force measurement and reducing the human burden during measurement.

[0148] Furthermore, since the connecting spring is configured to be interposed between the disc body to which the probe body is attached and the horizontal mounting base, facing downwards, the pressing reaction force from the bolt end face can be reliably received by the disc body via the probe body according to the inclination gradient of the bolt end face, and the connecting spring can be elastically deformed to contract according to the inclination gradient. Therefore, as the connecting spring undergoes elastic deformation to contract, the disc body tilts and displaces, and the probe body, which is integrated with it, can tilt and displace stably from a standby position to a forward contact position.

[0149] Furthermore, since the connecting spring is wound around a spring guide rod located between the horizontal mounting base and the disc body, the spring guide rod can restrict the range of elastic deformation of the connecting spring and the displacement range of the disc body at the tip of the arm to a certain range, thereby stabilizing the positive contact posture of the probe body at the tip of the arm.

[0150] Furthermore, since the coupling medium is applied to the end face of the fastening bolt, it allows the probe body to be pressed and fitted to the end face of the fastening bolt with optimal conformity. As a result, the coupling medium conforms to the inclined irregularities on the bolt end face that occur during the manufacturing process, filling the gap between the bolt end face and the probe body, thereby improving the transmission of ultrasonic waves.

[0151] Furthermore, in a method for measuring the axial force of a fastening bolt using the fastening bolt axial force measuring device described in any one of claims 1 to 4, when measuring the axial force of the fastening bolt with the probe, the measured value of the axial force of the fastening bolt before fastening the fastened members together and the measured value of the axial force of the fastening bolt after fastening the fastened members together are compared and calculated, and the appropriateness of the axial force of the fastening bolt is determined based on the difference. As a result, the measurement value acquisition operation is automated to obtain the measured value at an appropriate timing, preventing variability in the axial force measurement results, and furthermore, because the appropriateness of the axial force is automated, the evaluation inspection results can be determined immediately, which has the effect of saving labor and improving the efficiency of inspection work.

[0152] In other words, according to the present invention, it is possible to automate part of the exploration operation during ultrasonic axial force measurement, thereby reducing the human burden during measurement, and to easily and automatically adjust the probe to a correct contact position in which it is accurately tilted toward the unevenly inclined surface of the bolt end, which has individual differences, and contacts it with an appropriate pressing force, thereby improving the accuracy of axial force measurement. This provides a fastening bolt axial force measuring device and a fastening bolt axial force measuring method using the same device. [Explanation of Symbols]

[0153] A fastening bolt axial force measuring device 1. Robot arm 2 transducer 3. Horizontal mounting base 4 Linked Springs 40 Spring guide rod 5 Discs

Claims

1. A printing device for printing bolt information on the end face of a fastening bolt before fastening, A robotic arm with an imaging camera attached to its tip, A pre-measurement work area is provided where a bolt-standing container is arranged, which houses multiple fastening bolts in an upright position with their end faces, on which the bolt information is printed, protruding upwards. The wheel is positioned after the brake disc has been fastened with fastening bolts, and the measurement work area is set up after the wheel has been positioned. It includes a monitor unit that displays various conditions and measurement results, and further, The horizontal mounting base at the tip of the robot arm, A probe having a probe body disposed below the horizontal mounting base and measuring the bolt length from the end face of the fastening bolt by transmitting and receiving ultrasonic waves, A connecting spring interposed between the horizontal mounting base and the probe body to press the probe body against the end face of the fastening bolt, The device comprises the printing device, probe, imaging camera, robot arm, and control unit electrically connected to the monitor unit, An axial force measuring device for measuring the axial force of fastening bolts for attaching brake discs to the wheels of a rail vehicle, using a probe mounted below the horizontal mounting base at the tip of the robot arm, The control device is A bolt information assignment process that controls the printing device to print bolt information on the end face of the fastening bolt, The robot arm is controlled to read bolt information printed on the end face of each fastening bolt in the bolt-standing container placed in the pre-measurement work area using the imaging camera and transmit it to the control device, the probe is brought face to face with the end face of the bolt coated with coupling medium and brought into contact with it to achieve a normal contact position, the probe is rotated back and forth, the operation is stopped and the system waits for a certain period of time, and then the probe is used to obtain a measurement value of the fastening bolt and the obtained measurement value is stored in the control device as an axial force pre-measurement process. The post-axial force measurement process involves the robot arm controlling the imaging camera to read bolt information printed on the end face of each fastening bolt of a wheel that has been fastened with fastening bolts that have undergone the pre-axial force measurement process and is positioned in the post-measurement work area, and transmitting this information to the control device. The probe is then brought into contact with the end face of the bolt coated with a coupling medium, and the probe is brought into contact with the end face to achieve a normal contact position. The probe is then rotated back and forth, and after the operation stops, the system waits for a certain period of time. After that, the probe is used to acquire measurement values ​​of the fastening bolts, and the obtained measurement values ​​are stored in the control device. An axial force measuring device is configured to perform an appropriate axial force determination process, which involves calculating the axial force based on the difference between the measurement value in the pre-axial force measurement process and the measurement value in the post-axial force measurement process, determining that the fastening bolt is normal if the axial force is within a predetermined appropriate axial force range, determining that the fastening bolt is abnormal if it deviates from that range, sending a stop signal to the robot arm and an abnormality signal for the abnormal fastening bolt to the monitoring unit to notify the operator of the fastening bolt with abnormal axial force.

2. A printing device for printing bolt information on the end face of a fastening bolt before fastening, A robotic arm with an imaging camera attached to its tip, A pre-measurement work area is provided where a bolt-standing container is arranged, which houses multiple fastening bolts in an upright position with their end faces, on which the bolt information is printed, protruding upwards. The wheel is positioned after the brake disc has been fastened with fastening bolts, and the measurement work area is set up after the wheel has been positioned. It includes a monitor unit that displays various conditions and measurement results, and further, The horizontal mounting base at the tip of the robot arm, A probe having a probe body disposed below the horizontal mounting base and measuring the bolt length from the end face of the fastening bolt by transmitting and receiving ultrasonic waves, A connecting spring interposed between the horizontal mounting base and the probe body to press the probe body against the end face of the fastening bolt, The device comprises the printing device, probe, imaging camera, robot arm, and control unit electrically connected to the monitor unit, A method for measuring axial force using an axial force measuring device that measures the axial force of fastening bolts for attaching brake discs to the wheels of a rail vehicle by means of a probe mounted below the horizontal mounting base at the tip of the robot arm, The control device is A bolt information assignment process that controls the printing device to print bolt information on the end face of the fastening bolt, The robot arm is controlled to read bolt information printed on the end face of each fastening bolt in the bolt-standing container placed in the pre-measurement work area using the imaging camera and transmit it to the control device, the probe is brought face to face with the end face of the bolt coated with coupling medium and brought into contact with it to achieve a normal contact position, the probe is rotated back and forth, the operation is stopped and the system waits for a certain period of time, and then the probe is used to obtain a measurement value of the fastening bolt and the obtained measurement value is stored in the control device as an axial force pre-measurement process. The post-axial force measurement process involves the robot arm controlling the imaging camera to read bolt information printed on the end face of each fastening bolt of a wheel that has been fastened with fastening bolts that have undergone the pre-axial force measurement process and is positioned in the post-measurement work area, and transmitting this information to the control device. The probe is then brought into contact with the end face of the bolt coated with a coupling medium, and the probe is brought into contact with the end face to achieve a normal contact position. The probe is then rotated back and forth, and after the operation stops, the system waits for a certain period of time. After that, the probe is used to acquire measurement values ​​of the fastening bolts, and the obtained measurement values ​​are stored in the control device. A method for measuring axial force, characterized by performing an appropriate axial force determination process which involves calculating the axial force based on the difference between the measurement value in the pre-axial force measurement process and the measurement value in the post-axial force measurement process, determining that the fastening bolt is normal if the axial force is within a predetermined appropriate axial force range, determining that the fastening bolt is abnormal if it deviates from that range, sending a stop signal to the robot arm and an abnormality signal for the abnormal fastening bolt to the monitoring unit to notify the operator of the fastening bolt with abnormal axial force.

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