Fastening tool

Abstract

To increase the efficiency of a connection work of a steel material.SOLUTION: An attachment 30 having a socket 31 engageable with a nut 16 is mounted on an impact trench 20 used for primary fastening of a high strength bolt 15 and the nut 16 at a steel bridge construction site. The socket 31 is rotated by turning ON a trigger provided on the impact trench 20 by a user. The attachment 30 includes a marking mechanism 32 for marking the high strength bolt 15, the nut 16, a washer 17 and a splice plate 13. The marking mechanism 32 is operated after a fastening torque reaches a first specified value during the primary fastening.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a fastening tool. [Background technology]

[0002] At steel bridge construction sites and the like, connection work is performed in which multiple steel materials are connected using fasteners (bolts, washers, nuts). In this connection work, it is common to perform primary tightening to a specified tightening torque before final tightening of the fasteners, and then mark the bolts, washers, nuts, and steel materials with a pen or the like. After final tightening, the markings can be visually checked to see if there has been any forgetting to tighten or co-rotation. In recent years, a technology has been proposed that uses a cap-type auxiliary tool that is placed over the fasteners when marking (see, for example, Patent Document 1), which aims to improve the efficiency of marking and, ultimately, the efficiency of the connection work. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-108565 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when connecting multiple steel materials, the number of fasteners required increases as the size of the steel materials increases. For example, thousands to tens of thousands of fasteners may be used per steel bridge. Even if the above-mentioned marking auxiliary tools are used, the connecting work (especially marking) still requires a great deal of time because the auxiliary tools must be repeatedly attached and detached. As such, there is still room for improvement in the efficiency of the connecting work with regard to marking after the primary tightening.

[0005] The present invention has been made in consideration of the above-mentioned problems, and a main object of the present invention is to improve the efficiency of the connecting work of steel materials. [Means for solving the problem]

[0006] The present invention is a tightening tool (impact wrench 20) that is equipped with a socket (socket 31) that can engage with a nut (nut 16), has a drive unit (motor 22) that rotates the socket based on a predetermined operation by the user (ON operation of trigger 28), and is used for the primary tightening of the nuts and bolts (high-strength bolt 15) corresponding to the nuts during connection work to connect multiple steel materials (bridge girders 11-12, splice plates 13-14) using the nuts and bolts, and is equipped with a marking mechanism (marking mechanism 32) that automatically marks multiple objects including the nut, the shaft of the bolt, and / or the steel materials when the primary tightening is completed based on the predetermined operation. Effect of the Invention

[0007] According to the present invention, after the primary tightening, marking is performed by the tightening tool. With this configuration, both the primary tightening and marking can be performed without changing the tool. Therefore, it is possible to reduce the work time and preparation time for marking and improve the work efficiency in the work of connecting steel materials. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view showing a bridge girder connection structure according to the first embodiment. [Diagram 2] FIG. [Diagram 3] Side view of an impact wrench. [Figure 4] FIG. [Diagram 5] 6 is a flowchart showing a control process for primary tightening. [Figure 6] FIG. 11 is a schematic view showing a cross section of an attachment according to a second embodiment. [Figure 7] FIG. 11 is a schematic view showing a vertical cross section of an attachment according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <First embodiment> Hereinafter, a first embodiment of the impact wrench used at steel bridge construction sites, etc. will be described with reference to the drawings. First, a connecting structure of a steel bridge 10 will be described with reference to FIG.

[0010] The connection structure of the steel bridge 10 comprises a plurality of bridge girders (bridge girders 11, 12) arranged in a series and splice plates (splice plates 13, 14) arranged to sandwich the boundary portions of the bridge girders, and the bridge girders 11, 12 and the splice plates 13, 14 (hereinafter, the bridge girders 11, 12 and the splice plates 13, 14 are also referred to as "steel materials") are connected using fasteners (high-strength bolts 15, nuts 16, washers 17). Specifically, the bridge girders 11, 12 and the splice plates 13, 14 have bolt holes formed in the overlapping direction of the steel materials. High-strength bolts 15 are inserted into the bolt holes from the splice plate 14 side (the lower side in FIG. 1), and the shafts 15a of the high-strength bolts 15 protrude from the splice plates 13. A nut 16 and a washer 17 are attached to this protruding portion, and the bridge girders 11, 12 are connected via the splice plates 13, 14 by tightening the steel material with a high-strength bolt 15 and a nut 16.

[0011] Next, the flow of the connecting work (connecting method) will be described with reference to Fig. 2. In the connecting work, first, primary tightening is performed so that the tightening torque of the high strength bolts 15 and nuts 16 becomes a first specified value. The first specified value is lower than the set upper limit (second specified value) of the tightening torque in the final tightening described later, and the primary tightening is performed to introduce tension evenly into the high strength bolts 15 before the final tightening (see Fig. 2(a)).

[0012] After the primary tightening, marking is performed on the high-strength bolt 15, nut 16, washer 17, and splice plate 13 (see FIG. 2(b)). In this marking process, the mark M formed on the high-strength bolt 15, nut 16, washer 17, and splice plate 13 forms a line extending across the high-strength bolt 15, nut 16, washer 17, and splice plate 13. In other words, a single line is composed of the mark Ma applied to the high-strength bolt 15, the mark Mb applied to the nut 16, the mark Mc applied to the washer 17, and the mark Md applied to the splice plate 13.

[0013] After marking, final tightening is performed so that the tightening torque becomes the second specified value (see FIG. 2(c)). After final tightening, the mark M of each fastener is visually checked to confirm whether the final tightening has been performed properly. For example, in the example shown in FIG. 2(c), for the first fastener from the left (fastener A), the marks Ma and Mc are on the extension line of the mark Md, but the mark Mb is not on the extension line, so it can be confirmed that only the nut 16 with the mark Mb has rotated, i.e., the final tightening has been performed properly. In contrast, in the second fastener from the left (fastener B), the mark Mc is on the extension line of the mark Md, but the marks Ma and Mb are not on the extension line, so it can be confirmed that the high-strength bolt 15 with the mark Ma and the nut 16 with the mark Mb have rotated, that is, there is a possibility that the high-strength bolt 15 and the nut 16 have rotated, and in the third fastener from the left (fastener C), the mark Ma is on the extension line of the mark Md, but the marks Mb and Mc are not on the extension line, so it can be confirmed that the nut 16 with the mark Mb and the washer 17 with the mark Mc have rotated, that is, there is a possibility that the nut 16 and the washer 17 have rotated. In the fourth fastener from the left (fastener D), the marks Ma, Mb, and Mc are all on the extension line of the mark Md, so it can be confirmed that the nut 16 is not tightened after the primary tightening, that is, there is a possibility that the work has been forgotten. In this way, the markings make it possible to know whether final tightening has been performed properly, and therefore the markings have a technical significance when performing work to connect steel materials using fasteners such as high-strength bolts 15. Note that for the second to fourth fasteners from the left, the fasteners will need to be replaced and the primary tightening will be performed again.

[0014] Here, since high strength is required for the connection of steel materials, the number of fasteners used may be enormous depending on the structure using high-strength bolts. For example, the number of fasteners in a single steel bridge can range from several thousand to tens of thousands. For these reasons, it is common to use an impact wrench in the primary tightening in consideration of improving work efficiency and reducing the workload. However, in the conventional flow of marking using a pen or an auxiliary tool after performing the primary tightening using an impact wrench, it is necessary to bring the pen close to the fastener or place the auxiliary tool while checking the position of the fastener, and there is still room for improvement in terms of improving work efficiency and reducing the workload. In this embodiment, one of the features is that a marking function is given to the impact wrench used for the primary tightening in order to further improve work efficiency and reduce the workload. Below, the impact wrench 20 will be described with reference to FIG. 3.

[0015] The impact wrench 20 has an output shaft 21, a motor 22 as a drive unit that rotates the output shaft 21, an angle sensor 23 that detects the rotation angle of the output shaft 21, a control unit 60 to which the motor 22 and the angle sensor 23 are connected, and a housing 24 in which these components are mounted. The housing 24 is provided with a grip 27 that is held by a user, and the grip 27 is provided with a trigger 28 that can be operated by the fingers of the hand holding the grip 27. The trigger 28 is connected to the control unit 60, and when the control unit 60 detects an ON operation of the trigger 28, a drive signal is output to the motor 22, and when the control unit 60 detects an OFF operation of the trigger 28 while the drive signal is being output, the output of the drive signal is stopped.

[0016] The impact wrench 20 is also provided with a torque setting unit 29 that is operated when setting an upper limit for the tightening torque (setting a first specified value), and the user can arbitrarily change the first specified value by operating the torque setting unit 29. The motor 22 of the impact wrench 20 is also provided with a torque detection unit (not shown) that detects the generated torque. The torque setting unit 29 and the torque detection unit are connected to a control unit 60, and the control unit 60 controls the rotation of the motor 22 so that the set first specified value is not exceeded. For example, if the upper limit is exceeded, the output of the drive signal to the motor 22 is stopped.

[0017] Next, a description will be given of the attachment 30 attached to the tip of the impact wrench 20. As shown in Fig. 4, the attachment 30 has a socket 31 for rotating the nut 16 and a marking mechanism 32 for performing the above-mentioned marking.

[0018] The socket 31 is cylindrical. An attachment portion 41 for the output shaft 21 is formed at one end (hereinafter also referred to as the base end) of the socket 31, and an engagement portion 42 for engaging with the nut 16 is formed at the other end (hereinafter also referred to as the tip end). When the socket 31 is attached to the output shaft 21, the central axis CL of the output shaft 21 and the central axis of the socket 31 are coaxial.

[0019] The socket 31 has a certain length so that it can accommodate the shank 15a of the high-strength bolt 15 when the engagement portion 42 and the nut 16 are engaged, and is formed so that the inner surface 31a of the socket 31 is in line with the shank 15a of the high-strength bolt 15, the nut 16, and the washer 17 when the primary tightening is completed.

[0020] The socket 31 is formed with a slit 43 penetrating from the inside to the outside, and a flat movable piece 44 is disposed in the slit 43. The movable piece 44 is held by the socket 31 in a state in which it can slide in a direction intersecting the central axis CL (a direction obtained by combining the radial direction of the socket 31 and the height direction of the socket 31), and by moving in the intersecting direction, it switches between a protruding state in which it protrudes from the slit 43 to the inner region IE of the socket 31 and a retracted state in which it is prevented from protruding from the slit 43 to the inner region IE. A sponge pad 45 is provided on the edge of the movable piece 44 that protrudes from the slit 43 when it is in the protruding state. As shown in FIG. 4(b), the pad 45 is formed in a substantially stepped shape, and in the protruding state, one side of the substantially stepped surface of the pad 45 is pressed against the shaft 15a of the high-strength bolt 15, the nut 16, the washer 17, and the splice plate 13. The movable piece 44 is filled with paint, and the paint is supplied to the pad 45. When the pad 45 is pressed against the high strength bolt 15 or the like, the paint adheres to the high strength bolt 15 or the like through the pad 45, and the above-mentioned mark M is formed.

[0021] A cylindrical cover member 50 is disposed on the outside of the socket 31, facing the outer circumferential surface of the socket 31 with a gap therebetween, and the slit 43 is covered by this cover member 50. The cover member 50 is attached to the housing 24 of the impact wrench 20, and is separate from the socket 31.

[0022] A slider 51 that is slidable parallel to the central axis CL (i.e., in the height direction of the socket 31) is disposed between the cover member 50 and the socket 31. The slider 51 is held by the cover member 50, and a solenoid 52 (see FIG. 3) that is a drive unit for the slider 51 is mounted on the cover member 50. The solenoid 52 is also connected to the control unit 60, and the control unit 60 controls the drive of the solenoid 52. Specifically, when a drive signal is output to the solenoid 52, the slider 51 moves toward the tip side of the socket 31, and when the drive signal to the solenoid 52 is stopped, the slider 51 moves toward the base end side of the socket 31.

[0023] When the movable piece 44 is in the retracted state, a part of the movable piece 44 (the receiving portion 46) protrudes onto the movement path of the slider 51. The movable piece 44 is biased to a position in the retracted state by a biasing member (not shown), and when a drive signal is output to the solenoid 52 and the slider 51 moves toward the tip end side of the socket 31, the slider 51 presses the receiving portion 46, and the movable piece 44 switches from the retracted state to the protruding state against the biasing force (see FIG. 4(a)→FIG. 4(b)). When the output of the drive signal to the solenoid 52 is stopped and the slider 51 moves toward the base end side of the socket 31, the pressure of the slider 51 on the receiving portion 46 is released, and the movable piece 44 switches from the protruding state to the retracted state due to the biasing force (see FIG. 4(b)→FIG. 4(a)).

[0024] Next, a control process for primary fastening executed by the control unit 60 will be described with reference to Fig. 5. This control process is executed when the trigger 28 is turned ON.

[0025] In the control process for primary tightening, first, the output of a drive signal to the motor 22 is started (S101), which rotates the nut 16 together with the socket 31. After that, on the condition that the ON operation of the trigger 28 continues (not shown), the torque is amplified until the actual tightening torque (hereinafter also referred to as the actual torque) reaches a first specified value (also referred to as the specified value) (S103: NO, S102). When the actual torque reaches the first specified value, the output of the drive signal to the motor is stopped (S104), and it is determined whether the socket 31 has rotated by 5° (reference angle) or more (S105). In the control unit 60 shown in this embodiment, angle information indicating the rotation angle of the socket 31 after the output of the drive signal is started based on the ON operation of the trigger 28 is stored, and the determination of step S105 is made based on this angle information and the above-mentioned reference angle.

[0026] If the socket 31 has rotated 5° or more (S105: YES), a marking process is executed (S106). Specifically, a drive signal is output to the solenoid 52 to move the slider 51 toward the tip side of the socket 31 and switch the movable piece 44 from the retracted state to the protruding state. As a result, the pad 45 of the movable piece 44 is pressed against the high-strength bolt 15 or the like, and the above-mentioned mark M is formed.

[0027] On the other hand, if the socket 31 has not rotated by 5° or more (S105: NO), it is assumed that the bolt has been tightened again after the completion of the primary tightening, and this control process is terminated without executing the marking process. Note that in this embodiment, the rotation angle of the socket 31 is referenced to determine whether marking is possible, but this is not limited to this. For example, it may be determined whether marking is possible based on the drive time (rotation time) of the motor 22. In other words, a configuration may be adopted in which marking is executed when the drive time of the motor has reached a reference time, and marking is not executed when the reference time has not been reached.

[0028] Based on the above configuration, the procedure of the above connecting work in this embodiment will be explained in more detail. After the actual torque reaches the first specified value and the primary tightening is completed, the engagement state with the nut 16 is maintained. More specifically, the impact wrench 20 is maintained in a state in which it is in contact with the steel material (splice plate 13). The impact wrench 20 shown in this embodiment has an automatic marking function, and after the primary tightening is completed, marking is automatically performed based on the fact that the above condition (S105) is established. The impact wrench 20 is provided with a lamp 25 (see FIG. 3). The lamp 25 is connected to the control unit 60, and the light emission is controlled by the control unit 60. During marking, the display mode of the lamp 25 corresponds to the marking being performed, and when marking is completed, the display mode is switched to the marking completion. For example, the light emission method of the lamp 25 may be changed, such as blinking the lamp 25 during marking and turning on the lamp 25 after marking is completed. Alternatively, the color of the lamp 25 may be changed, for example, by lighting the lamp 25 red during marking and lighting the lamp 25 blue after marking is completed. The impact wrench 20 is configured such that the nuts 16 and the like are covered by the attachment 30. Therefore, it is preferable to prevent the mark M from becoming an inappropriate shape by notifying the user that marking is being performed or that marking has been completed using the lamp 25. In addition, it is preferable to notify the user that marking has been completed in order to reduce unnecessary waiting time and improve work efficiency.

[0029] According to the first embodiment described above in detail, primary tightening and marking can be performed using the impact wrench 20. In this way, with a configuration that allows both primary tightening and marking to be performed without changing tools, it is possible to reduce the work time and preparation time related to marking and improve the work efficiency in the work of connecting steel materials. Since marking is performed automatically after primary tightening, it is possible to prevent the occurrence of redoing marking due to the user forgetting to operate it, etc.

[0030] Furthermore, when a bolt is tightened again after the primary tightening is completed, marking is avoided on the condition that the rotation angle of the socket 31 does not reach the reference angle. This is preferable in terms of preventing overlapping of markings.

[0031] <Second embodiment> The socket 31 attached to the impact wrench 20 is a component that is subjected to a large load during primary tightening. Simplifying the structure of the socket 31 is advantageous in terms of preventing a decrease in the strength of the socket 31, and preventing distortion of the socket 31 is preferable in terms of facilitating the primary tightening operation. One of the features of this embodiment is that it is designed to take such circumstances into consideration. Below, the above-mentioned design will be described with reference to FIG. 6, focusing on the differences from the first embodiment.

[0032] In the socket 31X constituting the attachment 30X, a plurality of slits 43X are formed at predetermined intervals in the circumferential direction about the central axis CL, two slits 43X are formed at 180° intervals in this embodiment. The slits 43X extend in the same direction as the central axis CL, and the opening on the inner peripheral surface 31aX side faces the shaft 15a of the high-strength bolt 15, the nut 16, the washer 17, and the splice plate 13. The movable piece 44 and the associated configuration shown in the first embodiment are not provided in the slit 43X, and the socket 31X is simplified.

[0033] The slit 43X is covered by a cylindrical cover member 50X surrounding the socket 31X. The cover member 50X is formed with a through-hole 54X penetrating from inside to outside, and the through-hole 54X and the slit 43X communicate with each other depending on the rotational position of the socket 31X. A plurality of nozzles 55X are arranged in the through-hole 54X so as to be aligned in the same direction as the central axis CL. Each nozzle 55X is fixed to the cover member 50X so that the nozzle faces the socket 31X. Each nozzle 55X is connected to a paint tank 57X via a pump 56X, and paint is supplied from the tank 57X to the nozzle 55X by operating the pump 56X. The pump 56X is connected to a control unit 60, and the paint supply / stop is controlled by the control unit 60.

[0034] When the primary tightening is completed, the positions of the slit 43X of the socket 31X and the nozzle 55X of the cover member 50X may be misaligned in the circumferential direction around the central axis CL (see FIG. 6(a)). If such a misalignment occurs, the pump 56X is controlled to spray paint after aligning the slit 43X of the socket 31X with the nozzle 55X of the cover member 50X.

[0035] In this alignment, first, the rotational position of the socket 31X (the position of the slit 43X) is identified based on information from the angle sensor 23, and the slit 43X is rotated in a predetermined direction (for example, clockwise, fastening direction) to perform alignment. As described above, in this embodiment, two slits 43X are formed at an interval of 180°. That is, the amount of rotation of the socket 31X related to alignment is in the range of 0° to 180°.

[0036] After the alignment is completed, paint is sprayed from the nozzle 55X, and the sprayed paint passes through the slit 43X and adheres to the shaft 15a of the high-strength bolt 15, the nut 16, the washer 17, and the splice plate 13. This results in the formation of the mark M. The nozzle 55X is disposed at a position that is closer to the operator, that is, at a portion that faces the grip 27. This is a device to make the mark M more easily visible to the user when the impact wrench 20 is removed and the mark M is checked.

[0037] <Third embodiment> In this embodiment, the marking configuration is different from that of the first embodiment. Specifically, one of the features is that the marking configuration is simplified without providing a configuration equivalent to the movable piece 44. Below, the characteristic configuration of this embodiment will be described with reference to Fig. 7, focusing on the differences from the first embodiment.

[0038] The socket 31Y that constitutes the attachment 30Y is formed so that, when the primary tightening is completed, the inner surface 31aY of the socket 31Y is in line with the high-strength bolt 15, nut 16, and washer 17, and the gap between the inner surface 31aY and the high-strength bolt 15, nut 16, and washer 17 is zero or very small.

[0039] A groove 48Y that is open to the inner area IE is formed on the inner circumferential surface 31aY. The groove 48Y extends across the high-strength bolt 15, the nut 16, and the washer 17, and one end (the lower end in the figure) of the groove 48Y reaches the side surface 31dY of the socket 31Y via the end surface 31bY on the tip side of the socket 31Y. At this end, the groove 48Y is also open to the splice plate 13. In other words, when the primary tightening is completed, a single flow path 47Y is formed by the groove 48Y, the high-strength bolt 15, the nut 16, the washer 17, and the splice plate 13.

[0040] Here, the socket 31Y is formed with a fine hole 49Y that connects the end face 31cY on the output shaft 21 side (base end side) of the socket 31Y with the other end of the groove 48Y, and the liquid paint is supplied to the groove 48Y through the fine hole 49Y. Specifically, a pump can be connected to an inlet 49aY of the fine hole 49Y. When the pump is operated, the paint in a tank attached to the pump flows into the fine hole 49Y. After the primary tightening is completed, the pump is operated to supply the paint to the flow path 47Y, and the pump stops after a certain amount of paint is supplied. The method of connecting the socket 31Y and the pump is arbitrary. For example, as in the second embodiment, it is preferable to rotate the socket 31Y before marking to align the inlet 49aY with the pump.

[0041] As shown in Figures 7(a) to 7(b), the supplied paint passes through the fine hole 49Y and the groove 48Y toward the outlet 48aY formed on the side surface 31dY of the socket 31Y. During this process, part of the paint adheres to the high strength bolt 15, the nut 16, the washer 17, and the splice plate 13, forming a linear mark M.

[0042] <Other embodiments> In each of the above embodiments, the mark M is formed across the high-strength bolt 15, nut 16, washer 17, and splice plate 13, which are fasteners, to make it possible to grasp various co-rotations and forgotten work. Although such a configuration is ideal, it is not denied that some components may be excluded from the marking target. For example, in order to check the co-rotation between the nut 16 and the high-strength bolt 15, it is sufficient to mark the high-strength bolt 15 and the nut 16, and in order to check the co-rotation between the nut 16 and the washer 17, it is sufficient to mark the nut 16 and the washer 17. Note that the application of the automatic marking by the impact wrench 20 is not limited to the primary tightening of the high-strength bolt. It is also possible to apply it to the primary tightening of a normal bolt. In this case, for example, it is preferable to mark only the bolt shaft and the nut. [Explanation of symbols]

[0043] 10...steel bridge, 11, 12...bridge girder, 13, 14...splice plate, 15...high strength bolt, 16...nut, 17...washer, 20...impact wrench, 22...motor, 26Z...marking operation unit, 28...trigger, 31...socket, 32...marking mechanism, 60...control unit.

Claims

1. A tightening tool is provided, which is equipped with a socket that can be engaged with a nut, has a drive unit that rotates the socket based on a predetermined operation by a user, and is used for primary tightening of the nuts and bolts during a connecting operation in which a plurality of steel materials are connected by the nuts and bolts corresponding to the nuts, A tightening tool equipped with a marking mechanism that automatically marks multiple objects including the nut, the shank of the bolt, and / or the steel material when the primary tightening is completed based on the specified operation.

2. 2. The tightening tool according to claim 1, wherein a groove is provided on a side surface of the socket, and the marking is made along the groove.

3. 3. The tightening tool according to claim 1, wherein the marking is not performed on the nuts for which the primary tightening has been completed.

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