Automatic fastening device

Abstract

To provide an automatic fastening device for maintaining the fastening force of a fastener and then maintaining the aseismic performance of a building while enhancing the degree of freedom in installation, reducing the cost, actualizing the simplification of work, and allowing automatic threading of a nut.SOLUTION: An automatic fastening device 1 includes an outer sleeve 20, an inner sleeve 30, a fastening member 40 inserted through the inner sleeve, and a compression coil spring 50 for pressing the inner sleeve toward a fitting part 42. An outer sleeve inner peripheral face 20a and an inner sleeve outer peripheral face 30a form a first guide part 60, and an inner sleeve inner peripheral face 30b and a fastening member outer peripheral facer 40a form a second guide part 70. When a gap G is caused between a nut 4 and a fixed member 14, the inner sleeve is pressed by the compression coil spring and moved to the fitting part 42 while being guided by a first guide part, whereby the fastening member is turned in the peripheral direction while being guided by a second guide part, and a nut is turned via the fitting part, and threaded to a screw part 2a until losing the gap.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to an automatic fastening device, and more particularly to an automatic fastening device used for fixing a member to be fixed together with a fastening member composed of a bolt having a threaded portion and a nut screwed onto the threaded portion.

Background Art

[0002] Patent Document 1 discloses a screw tightening tool including a spring having winding elasticity and a locking means for locking the spring in a state having winding elasticity. The tip side on the inner diameter side of the spring is engaged with a member to be tightened such as a bolt or a nut, and the rear end side on the outer diameter side of the spring is fixed to a member to which the member to be tightened is attached. The locking means includes a locking member for locking the spring in a state having winding elasticity and a locking release mechanism for releasing the locking of the locking member.

[0003] The locking release mechanism releases the locking of the locking member when fixing the rear end portion of the spring to the member to which it is attached. Thereby, even if a tightening operation is not performed with a constant tightening torque on a bolt or nut that has loosened due to vibration, the bolt or nut can be tightened with a constant tightening torque naturally. Moreover, even when the bolt or nut naturally loosens due to aging, so-called wood shrinkage occurs, a constant tightening torque can always be maintained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above screw fastener, the spring is directly engaged with a fastening member such as a bolt or a nut and is fixed to the mounted member by a fixing member. Therefore, in the mounted member, it is necessary to secure an installation space for the screw fastener in the radial direction of the nut or the like. Further, since an expensive spring is used, the cost is high. Furthermore, since the fixing member, that is, the screw must be driven into the mounted member through the annular portion, there is a problem that the installation work takes time.

[0006] The present invention has been made in view of such problems, and while increasing the degree of freedom of the installation location, reducing the device cost, and further simplifying the installation work, the nut is automatically screwed in to maintain the fastening force of the fastener against the fixed member. Thus, an object of the present invention is to provide an automatic fastening device capable of maintaining the seismic performance of a building.

Means for Solving the Problems

[0007] In order to achieve the above object, an automatic fastening device of the present invention is an automatic fastening device used to fix a member to be fixed together with a fastening member composed of a bolt having a threaded portion and a nut screwed onto the threaded portion, and includes a cylindrical outer sleeve having a fixing portion that prevents the rotation of the automatic fastening device with respect to the member to be fixed, a cylindrical inner sleeve disposed movably in the axial direction of the outer sleeve within the outer sleeve, and a fastening member disposed within the outer sleeve, being prevented from moving in the axial direction and allowed to rotate in the circumferential direction, inserted into the inner sleeve, having a fitting portion fitted to the nut at one end, and having an insertion hole through which the bolt protruding from the nut is inserted. The automatic fastening device further includes a compression coil spring that presses and biases the inner sleeve toward the fitting portion within the outer sleeve. An inner circumferential surface of the outer sleeve and an outer circumferential surface of the inner sleeve form a first guide portion over their axial directions, and an inner circumferential surface of the inner sleeve and an outer circumferential surface of the fastening member form a second guide portion over their axial directions. When a gap is generated between the nut and the member to be fixed, the inner sleeve is pressed and biased by the compression coil spring and moves toward the fitting portion while being guided by the first guide portion. As a result, the fastening member rotates in the circumferential direction while being guided by the second guide portion, and further, the nut rotates via the fitting portion. The nut is screwed into the threaded portion until the gap disappears.

Advantages of the Invention

[0008] According to the automatic fastening device of the present invention, it is possible to increase the degree of freedom of the installation location, reduce the device cost, and further simplify the installation work, while automatically screwing the nut to maintain the fastening force of the fastening member with respect to the member to be fixed, and thus maintain the seismic performance of the building.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, the automatic fastening device 1 according to an embodiment of the present invention will be described with reference to the drawings. Note that the concepts of "upper" and "lower" in the following description are within the scope of the drawings and can change according to the mounting situation of the automatic fastening device 1. FIG. 1 shows a front view of the automatic fastening device 1 in the installed state, and FIG. 2 shows a side view of the automatic fastening device 1 in the installed state. The automatic fastening device 1 (hereinafter, also simply referred to as the device 1) is used to fix a fixed member together with a fastener 6 composed of a bolt 2 having a threaded portion 2a and a nut 4 screwed onto the threaded portion 2a.

[0011] The following describes a specific installation example of the device 1. As shown in FIGS. 1 and 2, in a building having a column 8 and a base 12 placed on a foundation 10, a hold-down fitting (member to be fixed) 14 is attached to the column 8 to fix the column 8 to the base 12 so as not to come out of the base 12. The hold-down fitting 14 has a main body fixed to the column 8 with screws 16 and a bolt insertion portion 18. A bolt (here, an anchor bolt) 2 inserted through the bolt insertion portion 18 is fastened to the bolt insertion portion 18 with a nut 4. Here, due to shrinkage of the base 12 or loosening of the nut 4 caused by vibration, a gap may occur between the bolt insertion portion 18 and the nut 4.

[0012] The device 1 is mounted on the nut 4 above the bolt insertion portion 18 and automatically screws the nut 4 to eliminate the above gap. Thereby, the fastening force of the fastener 6 with respect to the hold-down fitting 14 is maintained, and thus the seismic performance of the building is maintained. Also, as shown in FIGS. 1 and 2, since the device 1 in the installed state has a compact structure in the radial direction of the nut 4, the device 1 can be installed in substantially the same area as the installation space of the hold-down fitting 14 along the column 8.

[0013] FIG. 3 shows a perspective view of the device 1 seen from above, FIG. 4 shows a perspective view of the device 1 seen from below, and FIG. 5 shows a longitudinal sectional view of the device 1 mounted on the nut 4. As shown in FIG. 5, the device 1 mainly includes a cylindrical outer sleeve 20, a cylindrical inner sleeve 30, a tubular fastening member 40, and a compression coil spring 50. The outer sleeve 20 has a fixing portion 22 for fixing the device 1 to the hold-down fitting 14. The fixing portion 22 is a plate-like portion protruding downward from the lower end (one end) of the outer sleeve 20 and is formed in pairs in the radial direction of the outer sleeve 20.

[0014] Specifically, each fixing part 22 contacts the bolt insertion part 18 of the hold-down fitting 14 in the installed state of the device 1. Thereby, when the device 1 operates and the fastening member 40 rotates, the device 1 itself is prevented from rotating together with the fastening member 40. As shown in FIG. 5, the inner sleeve 30 is disposed in the outer sleeve 20 so as to be movable in the axial direction (vertical direction) of the outer sleeve 20. The fastening member 40 is inserted into the inner sleeve 30 while being prevented from moving in the axial direction and allowed to rotate in the circumferential direction within the outer sleeve 20.

[0015] The fastening member 40 has a fitting portion 42 that fits into the nut 4 at the lower end (one end), and an insertion hole 44 through which the bolt 2 protruding from the nut 4 is inserted. The device 1 can complete the installation work of the device 1 while preventing the rotation of the device 1 with respect to the bolt insertion portion 18 by each fixing portion 22 with a simple operation of fitting the fitting portion 42 into the nut 4. Therefore, it is not necessary to fix the device 1 to the pillar 8 with screws or the like.

[0016] A pin-shaped locking member 46 that holds the compression coil spring 50 in a compressed state is attached to the upper end of the fastening member 40. By attaching the locking member 46, the compression coil spring 50 can be compressed so that the device 1 can be stored and transported. The compression coil spring 50 is disposed above the inner sleeve 30, and the upper end of the compression coil spring 50 is locked within the outer sleeve 20. The inner sleeve 30 is pressed and biased toward the fitting portion 42 by the compression coil spring 50 within the outer sleeve 20.

[0017] The inner peripheral surface 20a of the outer sleeve 20 and the outer peripheral surface 30a of the inner sleeve 30 form a first guide portion 60 over their axial directions. Specifically, the first guide portion 60 forms a linear meshing portion 62 that meshes with each other on the inner peripheral surface 20a of the outer sleeve 20 and the outer peripheral surface 30a of the inner sleeve 30 to linearly move the inner sleeve 30 along the axial direction.

[0018] Furthermore, an inner circumferential surface 30b of the inner sleeve 30 and an outer circumferential surface 40a of the fastening member 40 form a second guide portion 70 over the axial direction thereof. Specifically, the second guide portion 70 forms a spiral engagement portion 72 that engages with the inner circumferential surface 30b of the inner sleeve 30 and the outer circumferential surface 40a of the fastening member 40 so as to convert the above-described linear movement of the inner sleeve 30 into rotational movement in the circumferential direction of the fastening member 40.

[0019] FIG. 6 shows a perspective view of the outer sleeve 20, and FIG. 7 shows a longitudinal sectional view of the outer sleeve 20. On an inner circumferential surface 20a of the outer sleeve 20, linear concave grooves 24 (see FIG. 7) are formed in pairs at positions facing each other in the radial direction along the axial direction of the outer sleeve 20. Further, at the upper end of the outer sleeve 20, step portions 26 that prevent the rotation of the above-described locking member 46 (specifically, rotation in the clockwise direction in a top view in FIG. 6) are formed in pairs in the radial direction.

[0020] With the compression coil spring 50 disposed within the outer sleeve 20, the locking member 46 is rotated in FIG. 6 counterclockwise in a top view so as to overcome each step portion 26. As a result, the fastening member 40 rotates counterclockwise in a top view, the inner sleeve 30 is pulled upward, and the compression coil spring 50 is brought into a compressed state. In this state, the locking member 46 is hooked on each step portion 26 and held in a state where the rotation of the locking member 46 is prevented. Thereby, the compressed state of the compression coil spring 50 is maintained within the outer sleeve 20. Further, as described above, a pair of fixing portions 22 are formed at the lower end of the outer sleeve 20.

[0021] FIG. 8 shows a perspective view of the inner sleeve 30, and FIG. 9 shows a longitudinal sectional view of the inner sleeve 30. On the outer peripheral surface 30a of the inner sleeve 30, linear ridge portions 32 are formed in pairs at positions facing the respective linear concave groove portions 24 of the outer sleeve 20. The above-described linear engagement portion 62 is formed by the pair of linear concave groove portions 24 formed on the inner peripheral surface 20a of the outer sleeve 20 and the pair of linear ridge portions 32 formed on the outer peripheral surface 30a of the inner sleeve 30 meshing with each other. Further, a spiral concave groove portion 34 is formed on the inner peripheral surface 30b of the inner sleeve 30.

[0022] FIG. 10 shows a perspective view of the fastening member 40, FIG. 11 shows a longitudinal sectional view of the fastening member 40, and FIG. 12 shows a perspective view of the washer 48 attached to the upper end of the outer sleeve 20. On the outer peripheral surface 40a of the fastening member 40, a spiral ridge portion 52 is formed at a position facing the spiral concave groove portion 34 of the inner sleeve 30. At the upper end of the fastening member 40, a pair of locking holes 54 through which the above-described locking member 46 is inserted are formed. Further, as described above, a fitting portion 42 into which the nut 4 is fitted is formed at the lower end of the fastening member 40, and an insertion hole 44 for the bolt 2 is formed inside the fastening member 40.

[0023] The spiral engagement portion 72 is formed by the spiral concave groove portion 34 formed on the inner peripheral surface 30b of the inner sleeve 30 and the spiral ridge portion 52 formed on the outer peripheral surface 40a of the fastening member 40 meshing with each other. Further, a locking groove 56 is formed on the outer peripheral surface 40a at the upper end of the fastening member 40. The washer 48 shown in FIG. 12 has its inner teeth 48a locked in the locking groove 56 in a state of being attached to the upper end of the outer sleeve 20 (see FIGS. 3 and 5). Thereby, the fastening member 40 is prevented from moving in the axial direction and is allowed to rotate in the circumferential direction within the outer sleeve 20.

[0024] FIG. 13 shows a longitudinal sectional view of the apparatus 1 when a gap G occurs between the nut 4 and the bolt insertion portion 18 of the hold-down fitting 14. First, the locking member 46 is removed from the state shown in FIG. 5 to extend the compression coil spring 50, and the apparatus 1 is set. Then, it is assumed that a gap G as shown in FIG. 13 occurs between the nut 4 and the bolt insertion portion 18 due to the shrinkage of the base 12 or the loosening of the nut 4 caused by vibration. In other words, the gap G is formed by the bolt 2 moving slightly upward by the amount of the gap (see FIG. 4) between the nut 4 and the fitting portion 42 due to the shrinkage of the beam 8 or the loosening of the nut 4.

[0025] In this case, the inner sleeve 30 is pressed and biased by the compression coil spring 50 that has been further extended from the initial set state (state (1)). Next, the inner sleeve 30 moves linearly in the axial direction toward the fitting portion 42, that is, downward, while being guided by the first guide portion 60 (i.e., the straight meshing portion 62) (state (2)). Along with this, the fastening member 40 rotates in the circumferential direction, specifically, in the clockwise direction when viewed from above, while being guided by the second guide portion 70 (i.e., the spiral meshing portion 72) (state (3)).

[0026] Along with this, the nut 4 rotates in the clockwise direction when viewed from above through the fitting portion 42 (state (4)), the nut 4 is screwed onto the threaded portion 2a (state (5)), and a state without the gap G as shown in FIG. 5 is achieved. It should be noted that the transition from these states (1) to state (5) is actually instantaneously performed every time a minute gap G occurs, and thus is not a slow operation that can be visually observed.

[0027] As described above, the apparatus 1 of the present embodiment includes the outer sleeve 20, the inner sleeve 30, the fastening member 40, and the compression coil spring 50 described above, and eliminates the gap G formed between the nut 4 and the bolt insertion portion 18 by transitioning from the state (1) to the state (5) described above. Thereby, the fastening force of the fastener 6 with respect to the hold-down fitting 14 is maintained, and thus the seismic performance of the building is maintained.

[0028] In addition, since the device 1 in the installed state has a compact structure in the radial direction of the nut 4, the degree of freedom of the installation location of the device 1 can be increased. Further, since the compression coil spring 50, which is less expensive than the torsion spring, is used, the device cost can be reduced. Further, the installation work of the device 1 is completed by a simple operation of installing the device 1 while fitting the fitting portion 42 into the nut 4 and bringing the fixing portion 22 of the outer sleeve 20 into contact with the bolt insertion portion 18. Thereby, the rotation of the device 1 can be prevented without performing operations such as screwing, and the installation work of the device 1 can be significantly simplified compared to the conventional case.

[0029] More specifically, the first guide portion 60 forms a linear meshing portion 62 that meshes with the inner peripheral surface 20a of the outer sleeve 20 and the outer peripheral surface 30a of the inner sleeve 30 so as to linearly move the inner sleeve 30 along the axial direction. Further, the second guide portion 70 forms a spiral meshing portion 72 that meshes with the inner peripheral surface 30b of the inner sleeve 30 and the outer peripheral surface 40a of the fastening member 40 so as to convert the linear movement of the inner sleeve 30 into the circumferential rotation of the fastening member 40.

[0030] Furthermore, the linear meshing portion 62 is formed by meshing a pair of linear concave ridges 24 formed on the inner peripheral surface 20a of the outer sleeve 20 with a pair of linear convex ridges 32 formed on the outer peripheral surface 30a of the inner sleeve 30. On the other hand, the spiral meshing portion 72 is formed by meshing a spiral concave ridge 34 formed on the inner peripheral surface 30b of the inner sleeve 30 with a spiral convex ridge 52 formed on the outer peripheral surface 40a of the fastening member 40.

[0031] Thus, in the device 1, the first guide portion 60 and the second guide portion 70, that is, the linear meshing portion 62 and the spiral meshing portion 72 are positioned above the fitting portion 42 that fits into the nut 4. As a result, in the device 1, the mechanism that converts the linear movement of the inner sleeve 30 into the rotation of the fastening member 40 and thus the fitting portion 42 can be positioned at a location separated from the nut 4 that is the object to be fastened. Therefore, even when only a narrow space can be secured around the nut 4 and the device 1, the device 1 can be installed, and both an increase in the degree of freedom of the installation location of the device 1 and a simplification of the installation work can be effectively realized.

[0032] Furthermore, the fixing portion 22 protrudes from the lower end of the outer sleeve 20, is formed in pairs in the radial direction of the outer sleeve 20, and contacts the bolt insertion portion 18 to prevent the device 1 from rotating with respect to the bolt insertion portion 18 when the fastening member 40 rotates. As a result, with a simple configuration that only forms the fixing portion 22 protruding from the lower end of the outer sleeve 20, the device 1 can be fixed to the bolt insertion portion 18 without using screws or the like, so that the simplification of the installation work of the device 1 can be surely realized.

[0033] Also, the device 1 includes a locking member 46 that holds the compression coil spring 50 in a compressed state inside the outer sleeve 20. As a result, during the installation work of the device 1, it is not necessary to compress the compression coil spring 50, and the device 1 can be set by simply removing the locking member 46 and extending the compression coil spring 50. Therefore, further simplification of the installation work of the device 1 can be achieved.

[0034] With the above, the description of the embodiments of the present invention is completed. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention. For example, as described above, the linear meshing portion 62 is formed by the engagement of a pair of linear concave ridges 24 formed on the inner peripheral surface 20a of the outer sleeve 20 and a pair of linear convex ridges 32 formed on the outer peripheral surface 30a of the inner sleeve 30.

[0035] However, the straight engagement portion 62 may be formed with reversed concavities and convexities on the inner peripheral surface 20a of the outer sleeve 20 and the outer peripheral surface 30a of the inner sleeve 30. Similarly, the spiral engagement portion 72 may also be formed with reversed concavities and convexities on the inner peripheral surface 30b of the inner sleeve 30 and the outer peripheral surface 40a of the fastening member 40. Further, the first guide portion 60 may be a spiral engagement portion where a spiral concave groove portion and a spiral convex rib portion engage with each other instead of the straight engagement portion 62. In this case, the second guide portion 70 will form a straight engagement portion where a pair of straight concave groove portions and a pair of straight convex rib portions engage with each other respectively.

[0036] Also, in the apparatus 1 of the above embodiment, the outer sleeve 20 is arranged with the fixing portion 22 at the lower end, and the apparatus 1 is installed such that the fixing portion 22 of the outer sleeve 20 contacts the bolt insertion portion 18. However, it is not limited to this, and it is also possible to install the apparatus 1 with the fixing portion 22 of the outer sleeve 20 on the upper side. In this case, it is necessary to fix the apparatus 1 by some means to prevent it from falling.

[0037] Also, in the above embodiment, the apparatus 1 is used to maintain the fastening force of the fastener 6 with respect to the hold-down fitting 14 attached to the pillar 8. However, it is not limited to this, and the apparatus 1 can be widely used for fastening various woods where there is concern about wood shrinkage, and various materials other than wood where there is concern about loosening of the nut 4 due to vibration, such as metal materials and resin materials.

Explanation of Reference Numerals

[0038] 1 Automatic fastening device 2 Bolt 2a Threaded portion 4 Nut 6 Fastener 14 Hold-down fitting (member to be fixed) 20 Outer sleeve 20a Inner peripheral surface of outer sleeve 22 Fixing portion 24 Straight concave groove portion 30 Inner sleeve 30a Outer peripheral surface of inner sleeve Inner peripheral surface of the 30b inner sleeve 32 Straight rib portion 34 Spiral groove portion 40 Fastening member Outer peripheral surface of the 40a fastening member 42 Fitting portion 44 Insertion hole 46 Locking member 50 Compression coil spring 52 Spiral rib portion 60 First guide portion 62 Straight meshing portion 70 Second guide portion 72 Spiral meshing portion G Gap

Claims

1. An automatic fastening device used to fix a member to be fixed together with a fastening member composed of a bolt having a threaded portion and a nut screwed onto the threaded portion, a cylindrical outer sleeve having a fixing portion for preventing rotation of the automatic fastening device with respect to the member to be fixed, a cylindrical inner sleeve disposed movably in the axial direction of the outer sleeve within the outer sleeve, within the outer sleeve, a fastening member that is prevented from moving in the axial direction and allowed to rotate in the circumferential direction, is inserted into the inner sleeve, has a fitting portion fitted to the nut at one end, and has an insertion hole through which the bolt protruding from the nut is inserted, a compression coil spring that presses and biases the inner sleeve toward the fitting portion within the outer sleeve and is provided with, the inner peripheral surface of the outer sleeve and the outer peripheral surface of the inner sleeve form a first guide portion over their axial directions, the inner peripheral surface of the inner sleeve and the outer peripheral surface of the fastening member form a second guide portion over their axial directions, when a gap is generated between the nut and the member to be fixed, the inner sleeve is pressed and biased by the compression coil spring and moves toward the fitting portion while being guided by the first guide portion, whereby the fastening member rotates in the circumferential direction while being guided by the second guide portion, and further the nut rotates via the fitting portion, and the nut is screwed into the threaded portion until the gap disappears. An automatic fastening device.

2. The first guide portion forms linear engagement portions that engage with each other on the inner peripheral surface of the outer sleeve and the outer peripheral surface of the inner sleeve to linearly move the inner sleeve along the axial direction, The second guide portion forms spiral engagement portions that engage with each other on the inner peripheral surface of the inner sleeve and the outer peripheral surface of the fastening member to convert the linear movement of the inner sleeve into rotational movement in the circumferential direction of the fastening member. The automatic fastening device according to Claim 1.

3. The automatic fastening device according to Claim 2, wherein the linear engagement portion is formed by engagement of a pair of linear concave ridges formed on the inner peripheral surface of the outer sleeve and a pair of linear convex ridges formed on the outer peripheral surface of the inner sleeve.

4. The automatic fastening device according to claim 3, wherein the spiral engagement portion is formed by engagement of a spiral concave groove portion formed on the inner peripheral surface of the inner sleeve and a spiral convex rib portion formed on the outer peripheral surface of the fastening member.

5. The automatic fastening device according to claim 1, wherein the fixing portion projects from one end of the outer sleeve, is formed in a pair in the radial direction of the outer sleeve, and contacts the member to be fixed, thereby preventing rotation of the automatic fastening device with respect to the member to be fixed when the fastening member rotates.

6. The automatic fastening device according to claim 1, further comprising a locking member that holds the compression coil spring in a compressed state within the outer sleeve.

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