Screw fastening machine

Abstract

To improve a percentage of defect-free product.SOLUTION: A screw fastening machine 10 includes a body 22 having a guide hole 20 for guiding a supplied screw 12, and a chuck 24 supported on the body 22, to which the screw 12 is supplied from the guide hole 20, whose tip is opened / closed with support points (66 and 106) to the body 22 as centers. The screw fastening machine 10 includes energization members (72 and 112) for applying energization force in a close direction at which the tip of the chuck 24 is closed. The screw fastening machine 10 includes a fastening rod 26 for push-sending the screw 12 in the guide hole 20 into the chuck 24, and forming a state in which a head 14 of the screw 12 is held at the tip of the chuck 24. The tip of the chuck 24 has holding surfaces (90 and 130) parallel to an outer surface 14B of a head 14 of the screw 12 in a state in which the chuck 24 reaches an open angle to hold the head 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a screw fastener. [Background technology]

[0002] Patent Document 1 discloses a screw driving machine. The screw driving machine is provided with a chuck that clamps the head of a screw to be fastened. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 2-97531 Summary of the Invention [Problem to be solved by the invention]

[0004] In the screw tightening machine of Patent Document 1, when the chuck is opened to clamp the head of the screw, the clamping surface of the chuck is inclined with respect to the outer surface of the head of the screw. As a result, the head of the screw is clamped in a state of point contact with the chuck, and the screw clamped in the chuck is prone to falling over.

[0005] If the screw falls, it will cause a tightening error and lead to a decrease in the first-pass rate.

[0006] The present invention has been made in consideration of the above problems, and has as its object to enable an improvement in the first-run rate. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a screw fastening tool comprising: a main body having a guide hole for guiding a supplied screw; a chuck supported by the main body, into which the screw is supplied through the guide hole and whose tip opens and closes around a support point with respect to the main body; a biasing member that applies a biasing force in a closing direction so that the tip of the chuck closes; and a tightening rod that pushes the screw in the guide hole into the chuck and can form a state in which the head of the screw is held by the tip of the chuck, wherein the tip of the chuck has a holding surface that is parallel to the outer surface of the head of the screw when the chuck is at an opening angle that holds the head. [Effects of the Invention]

[0008] According to one aspect of the present invention, the holding surface of the chuck is parallel to the outer surface of the head of the screw when it is at an opening angle that holds the head of the screw, so that the holding surface of the chuck that holds the screw is in surface contact or line contact with the outer surface of the head of the screw.

[0009] Therefore, compared to when a holding surface that is inclined relative to the outer surface of the head of the screw makes point contact with the head, the tilt of the held screw is suppressed, and the screw tightening machine can reduce tightening errors caused by the tilt of the screw, thereby improving the straight yield rate. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing a screw fastener according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the tip of the chuck showing a state in which a screw is supplied to the chuck. [Figure 3] FIG. 3 is a cross-sectional view of the tip of the chuck showing a state in which the head of the screw is held by the holding surface of the chuck. DETAILED DESCRIPTION OF THE INVENTION

[0011] A screw fastener 10 according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0012] Fig. 1 is a cross-sectional view showing a screw fastening tool 10 according to this embodiment. Fig. 2 is a cross-sectional view of the tip of the chuck 24 showing a state in which a screw 12 has been supplied to the chuck 24. Fig. 3 is a cross-sectional view of the tip of the chuck 24 showing a state in which the holding surfaces (90, 130) of the chuck 24 hold the head 14 of the screw 12, and Fig. 3 shows a state in which the chuck 24 has reached an open angle that holds the head 14 of the screw 12.

[0013] As shown in Figure 1, the screw fastening machine 10 is a device that screws a screw 12 into a target location and fastens it. The screw fastening machine 10 is used, for example, in an assembly device (not shown) that assembles a work by fastening the screw 12 into a threaded hole in the work. The main body 22 of the screw fastening machine 10 is attached to a mounting hole 42 of a slide plate 40 that moves back and forth between a screw supply device provided in the assembly device and the work, for example.

[0014] The screw 12 is composed of a bolt having a head 14 and a threaded portion 16 that extends from the head 14 and has a smaller diameter than the head 14. The head 14 is formed in a cylindrical shape. A hexagonal hole 18, for example, having a hexagonal shape, is formed in a top surface 14A of the head 14.

[0015] In this embodiment, the screw 12 is described as a bolt, but the screw 12 is not limited to a bolt. The screw 12 may be, for example, a wood screw that is screwed into a target location and tightened.

[0016] In addition, in this embodiment, the screw 12 having a hexagonal hole 18 formed in the head 14 is described as an example, but this embodiment is not limited to this configuration. The screw 12 may also be a screw 12 having a "-" or "+" groove formed in the head 14. In addition, the shape of the head 14 of the screw 12 is not limited to a cylindrical shape, and may be, for example, a hexagonal column shape.

[0017] The screw fastening tool 10 includes a main body 22 having a guide hole 20 that guides the screw 12 supplied from a screw supply device. The screw fastening tool 10 is supported by the main body 22, and includes a chuck 24 into which the screw 12 is supplied through the guide hole 20 and whose tip opens and closes around a support point (66, 106) with the main body 22. The screw fastening tool 10 also includes a biasing member (72, 112) that applies a biasing force in a closing direction to close the tip of the chuck 24. Additionally, the screw fastening tool 10 includes a clamping rod 26 that pushes the screw 12 in the guide hole 20 into the chuck 24 and can create a state in which the head 14 of the screw 12 is held by the tip of the chuck 24.

[0018] (Main body) The main body 22 has a cylindrical portion 30 that surrounds the guide hole 20, and a first support portion 32 and a second support portion 34 that support the chuck 24. The tip of the cylindrical portion 30 extends further toward the tip side than the first support portion 32 and the second support portion 34. A base portion 36 that protrudes laterally is provided at the base end of the main body 22. When the main body 22 of the screw fastener 10 is inserted and set in a mounting hole 42 of a slide plate 40 of an assembly device, the base portion 36 is supported by the opening edge of the mounting hole 42.

[0019] The guide hole 20 penetrates the main body 22 from the base end to the tip. A supply portion 46 having a larger diameter than the guide hole 20 is formed at the base end of the guide hole 20. The supply portion 46 forms a supply port for the screw 12. The guide hole 20 guides the screw 12 supplied from the supply portion 46 toward the tip side.

[0020] (Zipper) The chuck 24 includes a first gripping portion 50 and a second gripping portion 52 that are arranged to sandwich the cylindrical portion 30 having the guide hole 20 therebetween.

[0021] In this embodiment, the chuck 24 is described as being composed of a pair of a first gripping portion 50 and a second gripping portion 52, but the chuck 24 is not limited to this configuration. The chuck 24 may be composed of, for example, three or more gripping portions.

[0022] (first grip part) The first grip portion 50 has a first lever portion 60 extending along the tubular portion 30 and a first holding portion 62 provided at the tip of the first lever portion 60.

[0023] The first lever portion 60 has a central portion in the longitudinal direction supported by the first support portion 32 of the main body 22 via a first shaft portion 64. This allows the first grip portion 50 to tilt around a first support point 66, which is the center of the first support portion 32.

[0024] The first lever portion 60 has a first opposing surface 60A that faces the tubular portion side surface 30A, and is located closer to the base portion 36 of the main body 22 than the first support point 66. The first opposing surface 60A inclines in a direction away from the tubular portion side surface 30A as it extends from the first support point 66 toward the base end. This allows the first lever portion 60 to incline around the first support point 66 until the first opposing surface 60A comes into contact with the tubular portion side surface 30A.

[0025] The first lever portion 60 has a first spring hole 70 at the base end portion on the base portion 36 side of the main body 22. The first spring hole 70 houses a first biasing member 72 formed of a coil spring.

[0026] The first lever portion 60 has a first screw hole 76 at its tip end. A first setscrew 78 is threaded into the first screw hole 76, and the amount by which the first setscrew 78 protrudes from the first lever portion 60 can be adjusted. This allows the first lever portion 60 to tilt around the first support point 66 until the first setscrew 78 comes into contact with the tubular portion side surface 30A.

[0027] The outer surface of the first holding portion 62 is inclined toward the central axis C of the screw fastener 10 as it approaches the tip. The inner surface of the first holding portion 62 is formed as a curved surface.

[0028] The inner surface of the first holding portion 62 has a first base-side arcuate surface 80 that is arcuate and faces the tubular portion 30 of the main body 22 to prevent interference with the tubular portion 30, and a first step portion 82 that extends from the first base-side arcuate surface 80 along the end face of the tubular portion 30. The inner surface of the first holding portion 62 also has a first base-side tapered surface 84 that is inclined toward the central axis C as it extends from the first step portion 82 toward the tip side, and a first tip-side arcuate surface 86 that extends from the first base-side tapered surface 84 toward the tip side. The inner surface of the first holding portion 62 also has a first tip-side tapered surface 88 that is inclined toward the central axis C as it extends from the first tip-side arcuate surface 86 toward the tip side.

[0029] The inner surface of the first holding portion 62 is provided with a first holding surface 90 that extends toward the tip side from the first tip-side tapered surface 88. The first holding surface 90 is configured as a curved surface.

[0030] (Second grip part) The second grip portion 52 has a second lever portion 100 extending along the tubular portion 30 and a second holding portion 102 provided at the tip of the second lever portion 100.

[0031] The second lever portion 100 has a central portion in the longitudinal direction supported by the second support portion 34 of the main body 22 via a second shaft portion 104. The second grip portion 52 is tiltable around a second support point 106, which is the center of the second shaft portion 104.

[0032] The second lever portion 100 has a second opposing surface 100A that faces the tubular portion side surface 30A, and is located closer to the base portion 36 of the main body 22 than the second support point 106. The second opposing surface 100A inclines in a direction away from the tubular portion side surface 30A as it extends from the second support point 106 toward the base end. This allows the second lever portion 100 to incline around the second support point 106 until the second opposing surface 100A comes into contact with the tubular portion side surface 30A.

[0033] The second lever portion 100 has a second spring hole 110 at the base end portion on the base portion 36 side of the main body 22. The second spring hole 110 houses a second biasing member 112 made of a coil spring.

[0034] The second lever portion 100 has a second screw hole 116 at its tip. A second setscrew 118 is threaded into the second screw hole 116, and the amount by which the second setscrew 118 protrudes from the second lever portion 100 can be adjusted. This allows the second lever portion 100 to tilt around the second support point 106 until the second setscrew 118 contacts the cylindrical portion side surface 30A.

[0035] In the present embodiment, both the first gripping portion 50 and the second gripping portion 52 constituting the chuck 24 are configured to be tiltable, but the chuck 24 is not limited to this configuration. For example, the chuck 24 may be configured such that one of the first gripping portion 50 and the second gripping portion 52 is fixed and the other is tiltable.

[0036] The outer surface of the second holding portion 102 is inclined toward the central axis C of the screw fastener 10 as it approaches the tip. The inner surface of the second holding portion 102 is formed as a curved surface.

[0037] The inner surface of the second holding portion 102 has a second base-side arcuate surface 120 that is arcuate and faces the tubular portion 30 of the main body 22 to prevent interference with the tubular portion 30, and a second step portion 122 that extends from the second base-side arcuate surface 120 along the end face of the tubular portion 30. The inner surface of the second holding portion 102 also has a second base-side tapered surface 124 that is inclined toward the central axis C as it extends from the second step portion 122 toward the tip side, and a second tip-side arcuate surface 126 that extends from the second base-side tapered surface 124 toward the tip side. The inner surface of the second holding portion 102 also has a second tip-side tapered surface 128 that is inclined toward the central axis C as it extends from the second tip-side arcuate surface 126 toward the tip side.

[0038] The inner surface of the second holding portion 102 is provided with a second holding surface 130 that extends toward the tip side from the second tip-side tapered surface 128. The second holding surface 130 is formed of a curved surface.

[0039] The first holding portion 62 of the first gripping portion 50 and the second holding portion 102 of the second gripping portion 52 constitute the tip of the chuck 24 that can hold the head 14 of the screw 12. The first gripping portion 50 tilts about the first support point 66 and the second gripping portion 52 tilts about the second support point 106, thereby opening and closing the tip of the chuck 24.

[0040] 3, the first holding surface 90 of the first holding portion 62 constituting the tip of the chuck 24 is configured to be parallel to the outer surface 14B of the head 14 of the screw 12 when the chuck 24 is at an open angle to hold the head 14 of the screw 12. In addition, the second holding surface 130 of the second holding portion 102 constituting the tip of the chuck 24 is configured to be parallel to the outer surface 14B of the head 14 of the screw 12 when the chuck 24 is at an open angle to hold the head 14 of the screw 12.

[0041] In this embodiment, the head 14 of the screw 12 is cylindrical, and the first holding surface 90 and the second holding surface 130 are elliptical in an open state holding the head 14 of the screw 12. Therefore, when the tip of the chuck 24 holds the head 14 of the screw 12, parts of the first holding surface 90 and the second holding surface 130 come into line contact with the outer surface 14B of the head 14 along the axial direction 140 of the screw 12.

[0042] The contact area between each of the retaining surfaces 90, 130 and the outer surface 14B of the head 14 of the screw 12 has a width in the circumferential direction of the head 14. Therefore, in other words, the first retaining surface 90 and the second retaining surface 130 are in surface contact (surface abutment) with the outer surface 14B of the head 14.

[0043] Furthermore, by adjusting the curvature of the first retaining surface 90 and the second retaining surface 130, the contact area where the first retaining surface 90 and the second retaining surface 130 come into contact with the outer surface 14B of the head 14 can be expanded in the circumferential direction of the head 14.

[0044] (biasing member) 1, a first biasing member 72 as a biasing member is disposed in a compressed state between the end face of the first spring hole 70 and the cylindrical portion side surface 30A. The first biasing member 72 biases the first gripping portion 50 of the chuck 24 so that the first opposing surface 60A of the first lever portion 60 moves away from the cylindrical portion side surface 30A.

[0045] The second biasing member 112 constituting the biasing member is disposed in a compressed state between the end face of the second spring hole 110 and the cylindrical portion side surface 30A. The second biasing member 112 biases the second gripping portion 52 of the chuck 24 so that the second opposing surface 100A of the second lever portion 100 moves away from the cylindrical portion side surface 30A.

[0046] As a result, the first biasing member 72 and the second biasing member 112 constituting the biasing member apply a biasing force in the closing direction so that the tip of the chuck 24, which is composed of the first holding portion 62 of the first gripping portion 50 and the second holding portion 102 of the second gripping portion 52, closes.

[0047] (Tightening rod) The clamping rod 26 extends from a drive device (not shown) that is provided, for example, above the workpiece setting position of the assembly device. The drive device includes a rotation mechanism that rotates the clamping rod 26 and an elevator that raises and lowers the clamping rod 26 together with the rotation mechanism.

[0048] The fastening rod 26 has an engagement structure in which its tip engages with the head 14 of the screw 12. In this embodiment, which uses a screw 12 having a hexagonal hole 18 in its head 14, the fastening rod 26 is formed in the shape of a hexagonal column that can fit into the hexagonal hole 18 in the head 14 of the screw 12. The fastening rod 26 rotates and lowers the screw 12 engaged at its tip, thereby threading the screw 12 into the threaded hole in the workpiece and tightening it.

[0049] (Operation description) When the screw fastening tool 10 is used to fasten the screws 12 to the workpiece, the screw feeder of the assembly device feeds the screws 12 from the feeder 46 of the screw fastening tool 10 set on the slide plate 40 into the guide hole 20. The screws 12 are then guided along the guide hole 20 into the chuck 24.

[0050] The head 14 of the screw 12 guided into the chuck 24 is guided to the center of the chuck 24 along the base-end tapered surfaces 84, 124 of the gripping portions 50, 52 that make up the chuck 24. As a result, the screw 12 is temporarily held in the chuck 24 with the head 14 housed inside the tip-end arcuate surfaces 86, 126 of the holding portions 62, 102 (see FIG. 2).

[0051] In this state, the assembly device slides the slide plate 40 to move the screw fastening tool 10 to above the target location of the workpiece.

[0052] The assembly device also lowers the fastening rod 26 while rotating it using the drive device, and inserts the fastening rod 26 into the guide hole 20. Then, the tip of the fastening rod 26 engages with the head 14 of the screw 12 while being inserted into the hexagonal hole 18 of the head 14 of the screw 12 (see FIG. 2).

[0053] The driver then further lowers the fastening rod 26, causing the lower edge of the head 14 of the screw 12 to abut against the tip-side tapered surfaces 88, 128, spreading apart the holding portions 62, 102. As a result, the holding portions 62, 102 tilt about the support points 66, 106, and the chuck 24 operates in the opening direction, opening the tip portions.

[0054] When the head 14 of the screw 12 reaches the respective holding surfaces 90, 130 of the respective holding portions 62, 102, the outer surface 14B of the head 14 is clamped from the side by the respective holding surfaces 90, 130, and the screw 12 is held at the tip of the chuck 24 (see Figure 3).

[0055] At this time, each of the holding surfaces 90, 130 and the outer surface 14B of the head 14 of the screw 12 are in line contact on all four sides along the axial direction 140 of the screw 12. This prevents tilting of the screw 12. With this tilt-prevented state, the threaded portion 16 of the screw 12 is aligned with a screw hole in a target location, and then screwed into the screw hole and tightened into the target location.

[0056] (Action and effect) The main functions and effects of the screw fastening device 10 configured as above will now be described.

[0057] (1) The screw fastening tool 10 comprises a body 22 having a guide hole 20 that guides a supplied screw 12, and a chuck 24 that is supported by the body 22, into which the screw 12 is supplied through the guide hole 20, and whose tip opens and closes around a support point (66, 106) with respect to the body 22. The screw fastening tool 10 comprises a biasing member (72, 112) that applies a biasing force in a closing direction that closes the tip of the chuck 24. The screw fastening tool 10 comprises a clamping rod 26 that pushes the screw 12 in the guide hole 20 into the chuck 24 and can form a state in which the head 14 of the screw 12 is held by the tip of the chuck 24. The tip of the chuck 24 has a holding surface (90, 130) that is parallel to the outer surface 14B of the head 14 of the screw 12 when the chuck 24 is at an opening angle that holds the head 14.

[0058] According to this embodiment, the holding surfaces (90, 130) of the chuck 24 are parallel to the outer surface 14B of the head 14 of the screw 12 when the holding surfaces (90, 130) are at an opening angle that holds the head 14 of the screw 12. Therefore, the holding surfaces (90, 130) of the chuck 24 that hold the screw 12 are in line contact or surface contact (surface abutment) with the outer surface 14B of the head 14 of the screw 12.

[0059] Therefore, tilting of the held screw 12 is suppressed compared to when the holding surfaces (90, 130) inclined relative to the outer surface 14B of the head 14 of the screw 12 make point contact (point abutment) with the head 14. As a result, even when a large gap is formed between the countersunk hole and the head 14 of the screw 12, for example, the screw fastening device 10 can suppress fastening errors caused by tilting of the screw 12, thereby making it possible to improve the straight-through rate.

[0060] In this embodiment, the holding surfaces (90, 130) are in line contact from all sides with the outer surface 14B of the head 14 of the screw 12. As a result, the screw 12 held by the chuck 24 is positioned at the center of the chuck 24, improving the positioning accuracy of the screw portion 16 in the screw hole. Therefore, the screw fastening tool 10 makes it easy to align the screw portion 16 in the screw hole.

[0061] (2) In the screw fastening tool 10 , the tip of the chuck 24 holds the head 14 of the screw 12 and makes line contact with the outer surface 14 B of the head 14 along the axial direction 140 of the screw 12 .

[0062] In this embodiment, the screw 12 is held in a state where the chuck 24 and the outer surface 14B of the head 14 are in line contact along the axial direction 140 of the screw 12, thereby enhancing the effect of suppressing the tipping of the held screw 12.

[0063] Furthermore, in this embodiment, in which the screw 12 is rotated while the head 14 is held by the chuck 24, it is possible to suppress contact resistance during rotation compared to when the chuck 24 and the outer surface 14B of the head 14 are in surface contact over the entire circumference.

[0064] (3) In the screw tightening tool 10, the screw 12 is a bolt that is tightened by a tightening rod 26 that engages with the head 14.

[0065] In this embodiment, the screw tightening tool 10 can be used in assembly work using bolts.

[0066] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0067] In the above embodiment, the screw fastening device 10 is described as being used in an assembly device, but the method of using the screw fastening device 10 is not limited to this. For example, the screw fastening device 10 may be used alone. [Explanation of symbols]

[0068] 10 Screw tightening machine 12 screws 14 Head 14B External surface 20 Guide hole 22 Main Unit 24 Zipper 26 Clamping rod 66 First support point 72 First biasing member 90 First holding surface 106 Second support point 112 second biasing member 130 Second holding surface 140 axial direction

Claims

1. A screw tightening machine, a main body having a guide hole for guiding the supplied screw; a chuck supported by the main body, into which the screw is supplied through the guide hole, and whose tip opens and closes around a support point with the main body; a biasing member that applies a biasing force in a closing direction in which the tip end of the chuck closes; a clamping rod that pushes the screw in the guide hole into the chuck and that is capable of forming a state in which the head of the screw is held by the tip end of the chuck; Equipped with The tip of the chuck has a holding surface that is parallel to the outer surface of the head of the screw when the chuck is at an opening angle that holds the head. Screw tightening machine.

2. The screw fastener according to claim 1, the tip of the chuck comes into line contact with an outer surface of the head of the screw along the axial direction of the screw while holding the head of the screw; Screw tightening machine.

3. The screw fastening tool according to claim 1 or 2, The screw is a bolt that is tightened by the tightening rod engaging the head. Screw tightening machine.

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