load cell

Abstract

A load meter is provided that can manage the tensile force acting on a tendon by connecting it to a management device. [Solution] The load meter has a cylindrical strain-generating body and a cover, and the strain-generating body consists of a cylindrical anchor assembly, a cylindrical fixed object assembly, four shear beams connecting the anchor assembly and the non-fixed object assembly, the underside of the anchor assembly, the underside of the shear beams, a bottom plate continuous with the inner surface of the non-fixed object assembly, and strain gauges attached to the shear beams, and the top surfaces of the non-fixed object assembly and the shear beams are lower than the top surface of the anchor assembly by more than the thickness of the cover, and the cover is a hollow disk with a hollow portion and approximately the same diameter as the outer diameter of the non-fixed object assembly, and the space surrounded by the anchor assembly, non-fixed object assembly, shear beams, bottom plate and cover contains a sensor amplifier unit that measures load values, a control unit and a battery, and the control unit has a control and recording unit that converts the load values ​​into digital data and records them.

Description

[Technical Field]

[0001] The present invention relates to a load meter that measures the tensile force acting on a tendon such as an anchor bolt, and more particularly to a load meter that transmits the measured tensile force value to an external management device via wired / wireless communication. [Background technology]

[0002] Traditionally, various facilities have been installed inside tunnels to ensure safety and convenience, including lighting and ventilation equipment, which play an essential role in ensuring visibility for tunnel users and maintaining air quality.

[0003] These facilities are either buried in the tunnel structure, which is mainly made of concrete, or fixed to the tunnel walls or ceiling using anchor bolts. Anchor bolts are metal fasteners that are embedded in tunnel structures. They are inserted into holes drilled in the concrete and fixed in place by mechanical expansion or adhesives. The externally exposed male thread of the anchor bolt is then threaded onto the fixture to attach the equipment, and a set nut is screwed onto it and tightened, applying axial tension to the anchor bolt. This tension supports the weight of the equipment, withstands vibrations and shocks, and firmly secures the equipment.

[0004] A properly installed and correctly tensioned anchor bolt will provide a stable fixation for a long time, but prolonged use and environmental factors such as constant vibration, temperature changes, and humidity can cause the nut to loosen. As the loosening progresses, the tensile force acting on the anchor bolts decreases, reducing the fixing force of the equipment, posing a risk of the equipment falling. If the equipment falls, it could pose a serious hazard to vehicles and personnel passing through the tunnel. To prevent such dangers, it is necessary to visually check for loose nuts during inspections, as well as to measure the tensile strength of the anchor bolts as appropriate and take measures such as tightening them if necessary. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-162511 [Patent Document 2] Patent Publication No. 2021-167793 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 describes a ground anchor tension detection system that measures the tensile force (tension) of a ground anchor. In Patent Document 1, the tensile force of the ground anchor is measured by a strain sensor attached to the anchor plate, and the wiring of the strain sensor is connected to a monitor device via a connector provided on the outside of the anchor plate. However, the detection system of Patent Document 1 requires a circuit for operating the strain sensor and an A / D conversion circuit on the connected monitor device (see Figure 2), and simply connecting a general PC that does not have such circuits to the connector for connection makes it impossible to measure and monitor tensile force. It also describes that the strain sensor and the monitor device are connected by wireless communication (RFID), but does not describe at all how the wireless device should be positioned on the anchor plate.

[0007] Patent Document 2 describes a management system in which a sensing washer having a sensor and a communication unit is attached to a bolt and a nut, and the stress value of the sensing washer is monitored wirelessly. The sensing washer in Patent Document 2 houses the strain body and a communication unit placed outside the strain body in a non-metallic casing made of synthetic resin or the like, integrating them into one unit. Because the sensing washer is designed to protrude outside the strain body, it cannot be used in cases where the sensing washer interferes with the object being fixed. Furthermore, unlike metallic casings, non-metallic casings are prone to damage due to deterioration over time, so they need to be replaced periodically, which requires loosening and removing the nut before replacement.

[0008] An object of the present invention is to provide a load meter that can manage the tensile force acting on a tendon by connecting it to a conventional management device such as a personal computer via a wired or wireless connection. [Means for solving the problem]

[0009] The load meter of the present application, which has been made to achieve the above object, comprises a cylindrical strain generating body and a cover body covering the top of the strain generating body, the strain generating body being arranged on the inner periphery side and comprising a cylindrical anchor assembly having a tension member insertion hole in the center, a cylindrical fixed object assembly arranged on the outer periphery side, and a cylindrical fixing member assembly protruding from the outer periphery of the anchor assembly in a cross shape in a plan view, covered Four shear beams connected to the inner peripheral surface of the fixed object joint, the lower surface of the fixing tool joint, the lower surfaces of the four shear beams, covered The fixed object assembly includes a bottom plate that is continuous with the inner peripheral surface of the fixed object assembly, and strain gauges that are bonded to the four shear beams. covered The upper surface of the fixture assembly and the upper surface of the shear beam are lower than the upper surface of the anchor assembly by at least the thickness of the lid, and the lid has a hollow portion that fits into the upper part of the anchor assembly. covered The fixing member is a hollow disk-shaped member having a diameter substantially equal to the outer diameter of the fixing member assembly, and the fixing member is disposed inside the strain generating body and on the outer circumferential surface of the fixing member assembly. coveredA space surrounded by the inner peripheral surface of the fixed-object assembly, the side surface of the shear beam, the upper surface of the bottom plate, and the lower surface of the lid contains a sensor amplifier unit that is connected to the strain gauge and measures the load value acting on the strain element, a control unit that is connected to the sensor amplifier unit and records the load value, and a battery for driving the sensor amplifier unit and the control unit, and the control unit has a control and recording section that converts the load value sent from the sensor amplifier unit into digital data and records it. The control unit may be provided with a connection terminal on a side surface of the strain generating element or on an upper surface of the lid, the connection terminal being connected to the control and recording section and used to output the digital data to the outside. The device may further include a communication terminal connected to the connection terminal for transmitting the digital data to an external device via wireless communication. The control unit may have a communication section connected to the control and recording section and configured to transmit the digital data to an external device via wireless communication, and the lid may be made of a non-metallic material. [Effects of the Invention]

[0010] The present invention can achieve at least one of the following effects by solving the above-mentioned problems. (1) Since the sensor amplifier unit, recording unit, and battery are housed inside the strain generating body, these devices, which are provided protruding outside the strain generating body, do not interfere with the object to be fixed. (2) The measured load values ​​are saved and output as digital data, so a regular PC can be used as a control device. (3) By making the lid non-metallic and using a material that transmits radio waves, wireless communication with an external management device can be performed even when the communication unit is placed inside the internal space and sealed with the lid. (4) If the lid is made of a non-metal material such as synthetic resin, it may be damaged due to deterioration over time, but it can be replaced without loosening the nut. (5) The cover can be removed to perform maintenance on the sensor amplifier unit, recording unit, communication unit, etc., or to replace the battery, allowing measurements to be taken semi-permanently without loosening the nuts. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view of a load meter according to the present invention; [Figure 2] A perspective view of the load meter of the present invention (1) [Figure 3] Plan view of the strain-generating body [Figure 4] 1 is a plan view of a load cell according to the present invention; [Figure 5] Cross section AA of Figure 4 (sensor amplifier unit, control unit, and battery omitted) [Figure 6] Cross section B-B of Figure 4 [Figure 7] Sensor amplifier unit, control unit, and battery block diagram (1) [Figure 8] A perspective view of the load meter of the present invention (2) [Figure 9] Sensor amplifier unit, control unit, and battery block diagram (2) [Figure 10] Sensor amplifier unit, control unit, and battery block diagram (3) [Figure 11] A perspective view of the load meter of the present invention (3) DETAILED DESCRIPTION OF THE INVENTION

[0012] The load cell of the present invention will be described in detail below with reference to the drawings.

[0013] [Example 1] (1) Load cell configuration (Figs. 1-6) The load meter of the present invention comprises a strain generator 1, a cover 2 that covers the top of the strain generator 1, a sensor amplifier unit 3, a control unit 4, and a battery 5 that are housed in a space S inside the strain generator 1. The load meter is placed between the nut 7 and the object to be fixed 8, which is passed through the exposed part of the anchor bolt 6 fixed to the structure and fastened by tightening the nut 7 threaded onto the anchor bolt 6, and measures the load (tensile force acting on the anchor bolt 6) generated by tightening the nut 7.

[0014] (2) Strain body 1 The strain-generating body 1 is a cylindrical steel member, and consists of a cylindrical anchor assembly 11 located on the inner side and having a tension member insertion hole 111 in the center for inserting an anchor bolt 6, a cylindrical fixed object assembly 12 located on the outer side, four shear beams 13 protruding in a cross shape in a plan view from the outer surface of the anchor assembly 11 and connecting to the inner surface of the fixed object assembly 12, a bottom plate 14 connected to the underside of the anchor assembly 11, the undersides of the four shear beams 13 and the inner surface of the fixed object assembly 12, and eight strain gauges 15 attached to the four shear beams 13 (Figure 3). The upper surface of the anchor assembly 11 is joined to a nut 7 that screws onto the anchor bolt 6. The lower surface of the fixed-object assembly 12 is joined to the fixed object 8. A bottom plate 14, which is continuous with the lower surface of the anchor assembly 11 and the lower surface of the shear beam 13, is located higher than the lower surface of the fixed-object assembly 12. The load generated by tightening the nut 7 displaces the anchor assembly 11 downward, and strain is generated in the shear beam 13 due to shear force. This strain is measured as a resistance value by the strain gauge 15, thereby measuring the load generated by tightening the nut 7. The number of strain gauges 15 is not limited to eight, and can be selected appropriately depending on the type of strain gauge 15 used and the measurement method.

[0015] (3) Lid 2 The cover 2 is a member that covers the upper surfaces of the fixed object assembly 12 and the shear beams 13 of the strain generating body 1 . The cover 2 is a plate made of a non-metallic material such as synthetic resin, and is made of a material that allows radio waves generated from the control unit 4 housed inside the strain generating body 1 to pass through. The cover 2 is disk-shaped and has approximately the same diameter as the outer diameter of the object assembly 12, and has a hollow portion 21 that fits into the upper part of the fastener assembly 11. The upper surfaces of the object assembly 12 and the shear beam 13 are lower than the upper surface of the fastener assembly 11 by at least the thickness of the cover 2, so that they do not interfere with the nuts 7 or the tools used to tighten the nuts 7. The lid body 2 is fixed to the top surface of the strain-generating body 1 by screws 23 that are inserted into screw insertion holes 22 provided on the top surface on the outer periphery and screwed into threaded holes 121 provided on the top surface of the fixed-object assembly 12. If the size of the nut 7 can fit into the hollow portion 21, the lid body 2 can be removed while the nut 7 remains fastened to the anchor bolt 6. Since the lid body 2 is made of a non-metal material such as synthetic resin, it is subject to damage due to deterioration over time, but it can be replaced without loosening the nut 7.

[0016] (4) Arrangement of the sensor amplifier unit 3, control unit 4, and battery 5 Inside the flexure body 1, there are four spaces S surrounded by the outer circumferential surface of the anchor assembly 11, the inner circumferential surface of the fixed object assembly 12, the side surface of the shear beam 13, and the top surface of the bottom plate 14. In this embodiment, a sensor amplifier unit 3, a control unit 4, and a battery 5 are housed in each space S (FIG. 3), and the top is sealed with a lid 2. The sensor amplifier unit 3, the control unit 4, and the battery 5 are connected by wiring (not shown). By using a material that is transparent to radio waves for the lid 2, wireless communication with an external management device can be performed even when the lid 2 is sealed. Furthermore, because the sensor amplifier unit 3, the control unit 4, and the battery 5 are housed inside the flexure body 1, these devices, which are installed to protrude outside the flexure body 1, do not interfere with the fixed object 8. If the size of the nut 7 is such that it fits into the hollow portion 21 of the lid body 2, the lid body 2 can be removed while the nut 7 remains fastened to the anchor bolt 6 to perform maintenance on the sensor amplifier unit 3 and control unit 4 or replace the battery 5, allowing measurements to be performed semi-permanently without loosening the nut 7.

[0017] (5) Sensor Amplifier Unit 3 The sensor amplifier unit 3 is connected to the strain gauge 15 by wiring, controls the power supply of the strain gauge 15, and acquires the resistance value measured by the strain gauge 15. The acquired resistance value is sent to the control unit 4. The sensor amplifier unit 3 is also connected to a battery 5, and the power required for the operation of the sensor amplifier unit 3 is supplied from the battery 5.

[0018] (6) Control unit 4 (Figure 7) The control unit 4 is made up of a control and recording section 41, a communication section 42, and a temperature measurement section 43, and the power required for each operation is supplied from a battery 5. The resistance value sent from the sensor amplifier unit 3 is converted into digital data by the control and recording unit 41 and stored as a load value. The temperature measurement section 43 measures the temperature inside the control unit 4, and the measured value is stored in the control and recording section 41 as digital data. The communication unit 42 is a device for transmitting digital data of load values ​​and temperatures stored in the control and recording unit 41 via wireless communication with an external management device, and is composed of an antenna, a communication control circuit, etc. Since the resistance value and temperature data are converted into digital data by the control and recording unit 41, conventional wireless communication such as infrared, Wi-Fi, Bluetooth (registered trademark) can be used for communication with the management device. Also, a normal PC can be used as the management device. The digital data of the resistance value and temperature stored in the control and recording unit 41 is transmitted to an external management device at a predetermined time by the communication unit 42. In addition, if the external management device is unable to receive the transmitted data, the device may have a function to transmit the data all at once at the next transmission. In this embodiment, the control / recording unit 41 and the communication unit 42 are integrated, but they may be provided separately.

[0019] (7) Battery 5 The battery 5 supplies power to the sensor amplifier unit 3 and the control unit 4, and may be a dry cell, a storage battery, or the like. In this embodiment, the sensor amplifier unit 3, the control unit 4, and the battery 5 are separate, but some or all of them may be integrated.

[0020] (8) Waterproof structure (Figs. 5 and 6) The top of the space S inside the strain generating body 1 is sealed by the lid 2. A central O-ring 16 is provided between the outer peripheral surface of the fixing tool assembly 11 and the inner peripheral surface of the hollow portion 21 of the lid 2. A peripheral O-ring 17 is provided between the upper surface of the fixed object assembly 12 and the lower surface of the lid 2. This prevents water from entering the space S inside the strain generating body 1. The central O-ring 16 is accommodated in a central O-ring groove 211 provided on the inner peripheral surface of the hollow portion 21 of the lid body 2. The central O-ring groove 211 may be provided on the outer peripheral surface of the portion of the fastener assembly 11 that fits with the lid body 2, or may be provided at corresponding positions on the inner peripheral surface of the hollow portion 21 of the lid body 2 and the outer peripheral surface of the fastener assembly 11. The outer peripheral O-ring 17 is housed in an outer peripheral O-ring groove 122 provided on the upper surface of the fixed-object assembly 12. The outer peripheral O-ring groove 122 may be provided on the lower surface of the lid 2, or may be provided at corresponding positions on the upper surface of the fixed-object assembly 12 and the lower surface of the lid 2.

[0021] [Example 2] (1) Communication via connection terminal 44 In the above-described first embodiment, the control unit 4 inside the flexure body 1 is provided with a communication section 42 (FIG. 7) to perform wireless communication with an external management device, but a connection terminal 44 such as a USB for communicating with the outside of the flexure body 1 and outputting digital data may be provided on the side of the flexure body 1 (FIG. 8) without using the communication section 42. The connection terminal 44 may also be provided on the top surface of the lid 2. A communication terminal 45 such as a USB receiver may be connected to the connection terminal 44 to perform wireless communication with the management device (Figure 9), or a communication cable 46 may be connected to the connection terminal 44 and the management device to perform wired communication (Figure 10). It is possible to use both wireless communication and wired communication by using the communication unit 42 and the connection terminal 44. When wireless communication using the communication unit 42 is not performed, the lid 2 may be made of a metal that is not transparent to radio waves.

[0022] [Example 3] (1) Configuration of tendons and anchors In the above-mentioned Examples 1 and 2, the configuration of the tension member and the fixing device is an anchor bolt 6 and a nut 7, but the load meter of the present invention is not limited to this and can also be used with various combinations of tension members and fixing devices, such as a tension member made of PC steel wire 61, a wedge 71 that fixes the fixing device to the PC steel wire 61, and an anchor head 72 that fixes the wedge 71 with the PC steel wire 61 inserted, as shown in Figure 11. [Explanation of symbols]

[0023] 1 strain generating body, 11 anchoring tool joint, 111 tension member insertion hole, 12 fixed object joint, 121 screw hole, 122 outer peripheral O-ring groove, 13 shear beam, 14 bottom plate, 15 strain gauge, 16 central O-ring, 17 outer peripheral O-ring, 2 lid body, 21 hollow portion, 211 central O-ring groove, 22 screw insertion hole, 23 screw, 3 sensor amplifier units, 4 control unit, 41 control and recording unit, 42 communication unit, 43 temperature measurement unit, 44 connection terminal, 45 communication cable 5 batteries, 6 anchor bolts, 61 PC steel wire, 7 Nut, 71 Wedge, 72 Anchor head 8 Fixed object, S space

Claims

1. a cylindrical strain element; a cover that covers an upper portion of the strain generating body, The strain body is a cylindrical anchor assembly disposed on the inner circumferential side and having a tendon insertion hole at the center; a cylindrical object-to-be-fixed joined body disposed on the outer periphery; four shear beams that protrude in a cross shape in a plan view from the outer peripheral surface of the fixing tool assembly and are connected to the inner peripheral surface of the fixed object assembly; a bottom plate continuous with the lower surface of the fastener assembly, the lower surfaces of the four shear beams, and the inner peripheral surface of the fixed object assembly; strain gauges attached to the four shear beams; an upper surface of the fixed object assembly of the strain generating body and an upper surface of the shear beam are lower than an upper surface of the fixing tool assembly by at least the thickness of the lid body; the cover is a hollow disk-shaped body having a hollow portion that fits onto the upper portion of the fastener assembly and a diameter that is approximately the same as the outer diameter of the object assembly, Within the strain generating body, in a space surrounded by the outer peripheral surface of the fixing tool assembly, the inner peripheral surface of the fixed object assembly, the side surface of the shear beam, the upper surface of the bottom plate, and the lower surface of the lid, a sensor amplifier unit connected to the strain gauge and configured to measure a load value acting on the strain element; a control unit connected to the sensor amplifier unit and configured to record the load value; a battery for driving the sensor amplifier unit and the control unit; the control unit has a control and recording section that converts the load value sent from the sensor amplifier unit into digital data and records the digital data. Load cell.

2. The control unit is characterized in that a connection terminal for connecting to the control and recording unit and outputting the digital data to the outside is provided on a side surface of the strain generating body or an upper surface of the lid body.

2. The load cell according to claim 1.

3. a communication terminal connected to the connection terminal and configured to transmit the digital data to an external device via wireless communication; 3. The load cell according to claim 2.

4. the control unit has a communication section connected to the control and recording section and configured to transmit the digital data to an external device via wireless communication; The lid is made of a non-metallic material.

2. The load cell according to claim 1.

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