JP2017193052A - Fastening tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening tool capable of uniquely deciding whether it is a twice fastening or not.SOLUTION: A fastening tool comprises: fastening torque transmitting means for transmitting a fastening torque to a fastening member; fastening torque measuring means for measuring a fastening torque value; a torque limiter for actuating when the fastening torque value reaches a set torque value; fastening end detecting means for detecting the actuation of the torque limiter to output a fastening end detection signal; rotation angle detecting means for detecting a rotation angle of the fastening member; and twice fastening determining means. The twice fastening determining means uses a fastening torque value measured by the fastening torque measuring means, a fastening end detection signal, and a rotation angle detected by the rotation angle detecting means, as twice fastening discrimination information thereby to discriminate the presence or absence of the twice fastening on the basis of the rotation angle of the fastening member while the fastening end detection signal is acquired from the fastening start.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique capable of detecting that a fastening member such as a bolt already tightened with a set torque is tightened again.

  Conventionally, a system for managing whether or not a plurality of bolts are all tightened has been proposed (Patent Document 1).

  Such a management system transmits the position information of a tightening tool such as a torque wrench to a personal computer and manages the position of a fastening member such as a bolt. When the tightening tool performs tightening on the fastening member whose position has already been specified, a warning is issued to alert the operator, and the same fastening member is prevented from being tightened twice.

JP 2013-188858 A

  As in the past, in order to prevent double-tightening, a tightening tool such as a torque wrench and a personal computer or the like must communicate with each other by wire or wirelessly, and the position of a fastening member such as a bolt must be managed by the personal computer or the like. .

  For this reason, if it is possible to determine whether or not to tighten twice with only a tightening tool such as a torque wrench, management by communication with a personal computer or the like is not necessary.

  An object of the present invention is to provide a tightening tool capable of independently determining whether or not the tightening tool is tightened twice in order to solve such a problem.

  The tightening tool according to the present invention includes a tightening torque transmitting means for transmitting the tightening torque to the fastening member, a tightening torque measuring means for measuring the tightening torque value, and when the tightening torque value reaches the set torque value. A torque limiter that operates, a tightening completion detection unit that detects the operation of the torque limiter and outputs a tightening completion detection signal, a rotation angle detection unit that detects a rotation angle of the fastening member, and a double tightening determination unit Have. The twice tightening determination means uses the tightening torque value measured by the tightening torque measuring means, the tightening completion detection signal, and the rotation angle detected by the rotation angle detection means as the twice tightening determination information. Based on the rotation angle of the fastening member until the fastening completion detection signal is acquired, it is determined whether or not the fastening is performed twice.

  The twice-tightening determining means is configured such that when the rotation angle of the fastening member from the start of fastening to obtaining the fastening completion detection signal is equal to or less than the threshold angle, the fastening member that has already been fastened is tightened again. It can be determined as tightening.

  The double-tightening determination means determines the presence or absence of double-tightening based on the measured tightening torque value and the detected rotation angle of the fastening member from the start of tightening to the acquisition of the tightening completion detection signal. be able to. Specifically, the twice-tightening determination means has not yet completed the tightening when the ratio angle representing the ratio of the rotation angle of the tightening member to the measured tightening torque value is equal to or less than a preset threshold angle. It can be determined that the fastening member is fastened. The double-tightening determination means can determine that the fastening member that has already been tightened is double-tightened again when the specific angle exceeds the threshold angle.

  As the tightening tool, there is a torque wrench or a torque driver.

  According to the present invention, based on the rotation angle of a fastening member such as a bolt and the measured torque value, it can be determined by a tightening tool itself such as a torque wrench whether or not it is tightened twice.

Schematic which applied the fastening tool by this invention to the torque wrench. The block diagram of the electronic circuit of the torque wrench of FIG. The wave form diagram which shows the relationship between the torque value of 1st mode, and time. The wave form diagram which shows the relationship between the torque value of 2nd mode, and a rotation angle. The figure which shows the waveform of the first time fastening by angle measurement, and the twice fastening.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  1 is a schematic diagram in which the fastening tool according to the present invention is applied to a torque wrench, FIG. 2 is a block diagram of an electronic circuit of the torque wrench of FIG. 1, and FIG. 3 is a waveform diagram showing a relationship between a torque value and time in a first mode. FIG. 4 is a waveform diagram showing the relationship between the torque value and the rotation angle in the second mode.

  In FIG. 1, a torque wrench 1 is provided in the handle portion 2, a cylindrical handle portion 2, a head portion 3 that is a tightening torque transmitting means for transmitting a tightening torque to a fastening member 6 such as a bolt, and the like. A torque limiter 4, a socket 5 that is attached to a square shaft 32 of the head portion 3 and is fitted to a fastening member 6 such as a bolt, a strain gauge 7 as a tightening force detection sensor that is attached to the head portion 3, And a data acquisition unit 8 having a data transmission function. The square shaft 32 is connected to the head unit 3 via a one-way rotation mechanism such as a ratchet.

  The head portion 3 has a flat rod portion 33 extending rearward from the head main body portion 31 inserted into the handle portion 2 and is attached to the handle portion 2 so as to be rotatable via the support shaft 21.

  The torque limiter 4 constitutes a toggle mechanism, and includes a spring seat 41, a torque value setting spring 42, an adjustment screw shaft 43 constituted by a screw shaft that is not movable in the axial direction and can be rotated around the shaft, and a screw on the adjustment screw shaft 43. A nut member 44 to be joined, and a plate-like toggle 45 connected via a connecting pin (not shown) between the rear end portion of the rod portion 33 and the tip end portion of the spring seat 41 are provided. A torque value setting spring 42 is disposed between the spring seat 41 and the nut member 44. The toggle 45 is inclined with respect to an axis along the longitudinal direction of the handle portion 2 in a non-operating state of the torque limiter.

  When the fastening member 6 is fitted to the socket 5 and the handle portion 2 is gripped and turned in a predetermined direction, the fastening member 6 is tightened. When the set torque value is reached, the toggle 45 is moved relative to the axis. As a result, the spring seat 41 moves backward against the spring force of the torque value setting spring 42. As a result, transmission of the tightening force from the handle portion 2 to the head portion 3 is cut off. At this time, the handle portion 2 rotates relative to the head portion 3 with the support shaft 21 as a fulcrum. A toggle operation detection pin (not shown) is attached to the rod portion 33 of the head portion 3 and passes through an opening (not shown) formed in the handle portion 2. A through end portion of the toggle operation detection pin operates a tightening completion detection switch (not shown) attached to a circuit board 81 to be described later.

  That is, when the torque limiter 4 operates, the fastening completion detection switch moves toward the toggle operation detection pin and turns on. When the force applied to the handle portion 2 is weakened by the operation of the torque limiter 4, the torque limiter 4 returns to the original state, and the fastening completion detection switch is turned from ON to OFF.

  On the other hand, when tightening of the fastening member 6 is started, a detection signal of the strain gauge 7 is output to the data acquisition unit 8.

  The data acquisition unit 8 includes a circuit board 81 disposed in the exterior case 83 and a power supply battery (not shown). The exterior case 83 is provided with a display unit 84 that digitally displays a torque value, operation keys (not shown), and the like.

  In the present embodiment, the circuit board 81 is provided with a communication unit 86, an angular velocity sensor 87, a processor 80, and the like. As shown in FIG. 2, the processor 80 includes a torque value conversion unit 801 that acquires a torque value from a detection signal of the strain gauge 7, an angle conversion unit 802 that acquires a rotation angle from a detection signal of the angular velocity sensor 87, A tightening determination unit 803 is provided. The angular velocity sensor 87 detects the rotation of the handle portion 2.

  FIG. 2 shows a block diagram of the electronic circuit of the torque wrench 1.

  In FIG. 2, the processor 80, ROM 90, RAM 91, display unit 84, communication unit 86, angular velocity sensor 87, and strain gauge 7 are connected via a bus 92.

  The processor 80 includes a ROM 90 that stores a twice tightening determination program (shown in FIGS. 3 and 4) and a RAM 91 that provides the processor 80 with a temporary work area as memory units.

  In the present embodiment, as shown in FIG. 3, the torque value obtained by the conversion by the torque value conversion unit 801 is output to the communication unit 86 and the double tightening determination unit 803. The double-tightening determination unit 803 performs double-tightening determination as to whether or not the fastening member has already been tightened based on the waveform of the acquired torque value (first mode). As shown in FIG. 4, the double-tightening determination unit 803 determines whether the fastening member has already been tightened based on the acquired torque value waveform and the angle information converted by the angle conversion unit 802. The second tightening determination is performed (second mode).

  In the present embodiment, the first mode and the second mode can be selected by the operator looking at the display unit 84. Note that only the first mode or only the second mode may be provided.

  Next, the first mode shown in FIG. 3 will be described.

  Generally, when fastening a fastening member such as a bolt to a member to be fastened, which is a cylinder block of an engine part, for example, the bolt is tightened to a certain fastening force (this fastening is referred to as temporary fastening), and after temporary fastening, using a torque wrench The fastening member is tightened (this tightening is referred to as main tightening). In the final tightening, the ratchet operation is generally repeated a plurality of times until the tightening torque value reaches the set torque value.

  In FIG. 3, a torque value exceeding a threshold value (peak hold torque) is acquired with the vertical axis representing the torque value and the horizontal axis representing time.

  In FIG. 3, a torque waveform A indicated by a broken line indicates a case where a fastening member such as a bolt that has already been tightened with a set torque value is tightened by the torque wrench 1 of the present embodiment. Torque waveforms B1, B2, and B3 indicated by solid lines indicate a state in which the fastening members that have been temporarily tightened are finally tightened by the torque wrench of the present embodiment.

  The torque waveform A reaches the set torque value immediately after the tightening by the torque wrench 1 is started, and the fastening completion detection switch is turned on. That is, when the fastening member that has been temporarily tightened is finally tightened, at least one ratchet operation is required. However, when the fastening member that is finally tightened is tightened twice, there is no ratchet operation and the set torque value is reached. The completion detection switch is turned on.

  Therefore, if the ratchet operation is not detected between the start of tightening and the time when the tightening completion detection switch is turned on, the double tightening determination unit 803 determines that the tightening is twice and warns the display 84. Display. Also, a warning is given by a buzzer sound.

  On the other hand, when the temporarily tightened fastening member is finally tightened, first, the tightening by the torque waveform B1 is performed. Even if the torque wrench 1 is rotated within a certain rotation range, the tightening torque value is small, so that a ratchet operation for once rotating the handle portion 2 in the reverse direction is performed. During this ratcheting operation, no force is applied to the rod portion 33 of the head portion 3. For this reason, no signal is output from the strain gauge 7 affixed to the rod portion 33, and the torque value becomes zero.

  Next, when the handle portion 2 is rotated in the tightening direction, a torque waveform B2 is obtained. The torque waveform B2 has a torque value larger than that of the torque waveform B1, but has not yet reached the set torque value. Therefore, once the ratchet operation described above is performed, the handle portion 2 is rotated again in the tightening direction. As shown in the torque waveform B3, the final tightening is completed by the third tightening. In the torque waveform B3, the fastening completion detection switch is turned on at the peak of the torque value.

  The twice tightening determination unit 803 detects the ratchet operation during the period from the start of tightening until the tightening completion detection switch is turned on, so it is determined that the tightening is not performed twice, and the display unit 84 displays the tightening completion indication. Do.

  Therefore, according to the present embodiment, it is possible to determine whether or not the torque wrench 1 itself is tightened twice.

  Next, the second mode shown in FIG. 4 will be described.

  In FIG. 4, a torque waveform C indicated by a broken line indicates a case where a fastening member such as a bolt that has been completely tightened with a set torque value is tightened by the torque wrench 1 of the present embodiment. Torque waveforms D1, D2, and D3 indicated by two-dot chain lines, and a torque waveform E indicated by a solid line indicate a state in which the fastening member that has been temporarily tightened is finally tightened by the torque wrench 1 of the present embodiment.

  When the fastening member that has been completely tightened is tightened by the torque wrench 1 of the present embodiment, as shown by the waveform C, the handle portion 2 hardly rotates but the torque value increases rapidly. In this case, the specific angle representing the ratio of the screw rotation angle (θ) at the time of fastening of a fastening member such as a bolt to the screw fastening torque value (T) is Δθ1. When the set torque value is reached, the fastening completion detection switch is turned on.

  On the other hand, torque waveforms D1, D2, and D3 indicated by two-dot chain lines indicate a case where the ratchet operation is performed twice. The torque waveforms D1, D2, and D3 have a specific angle Δθ2 (Δθ1> Δθ2) representing a ratio of a screw rotation angle (θ) at the time of fastening of a fastening member such as a bolt to a screw fastening torque value (T). Temporarily, the ratio of the screw rotation angle (θ) at the time of fastening of a fastening member such as a bolt to the screw fastening torque value (T) of the torque waveform E when the torque wrench 1 is rotated to the set torque value without performing a ratchet operation. The expressed specific angle is also Δθ2.

  The peak hold torque corresponding to 0 degree at which the bolt starts rotating is determined by the torque wrench type (size). The angle threshold is set and changed according to the joint coefficient. The joint coefficient represents the tightening hardness of the screw and is inversely proportional to Δθ. When the joint coefficient is large, the tightening hardness of the screw is hard, and when it is small, the joint is soft. Therefore, the joint coefficient is stored in the ROM 90 according to the type of the fastening member, etc., and the peak hold torque is changed.

  That is, when determining the relative angle Δθ1 from the rotation angle of the handle portion 2 and the torque value, the double-tightening determining unit 803 determines that it is double-tightened even if the fastening completion detection switch is detected, and the display unit 84 Display the tightening. Also, warn twice with a buzzer.

  On the other hand, the double-tightening determination unit 803 determines that the final tightening has been performed when the ratio angle Δθ2 is obtained from the rotation angle and torque value of the handle unit 2 and detects that the fastening completion detection switch is ON, and then fastens to the display unit 84 Display completion. Here, the ratio angle Δθ3, which is a threshold value for determining whether or not to tighten twice, is stored in the ROM 90 in advance.

  Accordingly, if the calculated ratio angle Δθn is equal to or less than the threshold ratio angle Δθ3, it is determined that the temporarily tightened fastening member is finally tightened, and if the angle angle ratio angle Δθ3 is exceeded, it is tightened twice. Determine.

  In each of the embodiments described above, when the torque wrench 1 tightens a fastening member such as a bolt, it can be determined by the torque wrench itself whether or not it is tightened twice. For this reason, it is not necessary to discriminate twice tightening by communication with a management device such as a personal computer as in the prior art, and it is possible to easily discriminate twice tightening.

  In the double tightening determination in the first mode, the double tightening determination can be easily performed by using the presence or absence of the ratchet operation.

  In the second tightening discrimination in the second mode, even if there is no ratchet operation, a specific angle Δθ (T representing the ratio of the screw rotation angle (θ) at the time of fastening of a fastening member such as a bolt to the screw fastening torque value (T) / θ), it is possible to determine whether or not the tightening is performed twice.

  In each of the above-described embodiments, when the torque display and the management of torque data are unnecessary, a high-precision strain gauge is not necessary for measuring the torque waveform. Therefore, any sensor can be used as long as it can detect the bending stress at the time of torque load and can discriminate the increase in torque.

  Further, the tightening tool is not limited to a structure that is tightened by hand like a torque wrench or a torque driver, but may be an automatic drive structure.

  In the above-described embodiment, in the second mode, the ratio angle Δθ is compared with the angle threshold value to determine whether or not the tightening is performed twice, but the present invention is not limited to this. For example, as shown in FIG. 5, the first tightening is simply performed if the measured angle from the start of the angle measurement until the torque limiter of the torque wrench is activated (the fastening completion detection switch is ON) exceeds the threshold angle. If it is less than the threshold angle, it can be determined that double tightening has been detected. In this case, the torque limiter is actuated (the fastening completion detection switch is ON), and the first tightening is performed when the measurement angle is 35 degrees, and the second tightening is performed when the measurement angle is 2.5 degrees. Therefore, it is possible to determine whether or not to tighten twice based on the measurement angle by appropriately setting the threshold angle.

DESCRIPTION OF SYMBOLS 1 Torque wrench 2 Handle part 21 Support shaft 3 Head part 31 Head main body part 32 Square axis 33 Rod part 4 Torque limiter 41 Spring seat 42 Torque value setting spring 43 Adjustment screw axis 44 Nut member 45 Toggle 5 Socket 6 Fastening member 7 Strain gauge 8 Data acquisition unit 80 Processor 801 Torque value conversion unit 802 Angle conversion unit 803 Double tightening determination unit 81 Circuit board 83 Exterior case 84 Display unit 85 86 Communication unit 87 Angular velocity sensor 90 ROM 91 RAM 92 Bus

Claims (5)

A tightening torque transmitting means for transmitting the tightening torque to the fastening member;
A tightening torque measuring means for measuring a tightening torque value;
A torque limiter that operates when the tightening torque value reaches the set torque value;
Tightening completion detection means for detecting the operation of the torque limiter and outputting a tightening completion detection signal;
Rotation angle detection means for detecting the rotation angle of the fastening member;
The tightening torque measured by the tightening torque measuring means, the tightening completion detection signal, and the rotation angle detected by the rotation angle detecting means are used as the second tightening discrimination information, and the tightening is completed from the start of tightening. Based on the rotation angle of the fastening member until the detection signal is acquired, a double-tightening determination means for determining the presence or absence of double-tightening;
Tightening tool with   When the rotation angle of the fastening member from the start of tightening until obtaining the tightening completion detection signal is equal to or less than a threshold angle, the double-tightening determination unit retightens the fastening member that has already been tightened. The tightening tool according to claim 1, wherein the tightening tool is determined to be tightened twice.   The double-tightening determination means determines whether or not double-tightening is performed based on the measured tightening torque value and the detected rotation angle of the fastening member between the start of tightening and the acquisition of the tightening completion detection signal. The tightening tool according to claim 1, wherein the tightening tool is discriminated.   The double-tightening determination means tightens a fastening member that has not yet been tightened when a ratio angle representing a ratio of a rotation angle of the fastening member to a measured tightening torque value is equal to or less than a preset threshold angle. 2. The tightening according to claim 1, wherein when the ratio angle exceeds the threshold angle, it is determined that the fastening member that has already been tightened is double-tightened again. tool.   The tightening tool according to claim 1, wherein the tightening tool is a torque wrench or a torque driver.