Screw fastening machine

Abstract

The invention discloses a screw fastening machine which can improve the percent of pass. A screw fastening machine (10) is provided with: a main body (22) having a guide hole (20) for guiding a supplied screw (12); and a chuck (24) that is supported by the main body (22), that is supplied with the screw (12) from the guide hole (20), and that opens and closes at the tip thereof about support points (66, 106) with respect to the main body (22). The screw tightening machine (10) is provided with biasing members (72, 112) that apply biasing force in the closing direction in which the tip of the chuck (24) is closed. The screw fastening machine (10) is provided with a fastening rod (26) which 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 front end part of the chuck (24). The tip of the chuck (24) has holding surfaces (90, 130) parallel to the outer surface (14B) of the head (14) of the screw (12) in a state where the chuck (24) is at an open angle for holding the head (14).

Description

Technical Field

[0001] The invention relates to a screw fastening machine. Background Art

[0002] Patent Document 1 discloses a screw fastening machine. The screw fastening machine includes a chuck that grips the head of a screw to be fastened.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Utility Model Application Laid-Open No. 2-97531

[0006] Problems to be solved by the invention

[0007] In the screw tightening machine disclosed in Patent Document 1, when the chuck is opened to clamp the screw head, the clamping surface of the chuck is inclined relative to the outer surface of the screw head. Therefore, since the screw head is clamped in point contact with the chuck, the screw clamped by the chuck is prone to tilting.

[0008] If the screws are skewed, tightening errors will occur, resulting in a decrease in the yield rate. Summary of the Invention

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve the yield rate.

[0010] According to a certain embodiment of the present invention, a screw tightening machine is provided, which comprises: a main body, which has a guide hole for guiding the supplied screw; a chuck, which is supported by the main body, is supplied with the screw from the guide hole, and the front end is opened and closed with the support point of the main body as the center; a force-applying component, which applies a force in the closing direction of the front end of the chuck; a tightening rod, which 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 front end of the chuck, and the front end of the chuck has a holding surface parallel to the outer surface of the head of the screw when the chuck is in a state of holding the open angle of the head.

[0011] Effects of the Invention

[0012] According to a certain embodiment of the present invention, since the holding surface of the chuck is parallel to the outer surface of the screw head when the opening angle of the screw head is maintained, the holding surface of the chuck holding the screw is in surface contact or line contact with the outer surface of the screw head.

[0013] Therefore, compared to a case where the holding surface inclined relative to the outer surface of the screw head is in point contact with the head, the held screw is less likely to be skewed. This reduces tightening errors caused by skewed screws in the screw fastening machine, thereby improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a cross-sectional view showing the screw fastening machine according to this embodiment.

[0015] Figure 2 It is a cross-sectional view of the front end portion of the chuck showing a state in which a screw is supplied to the chuck.

[0016] Figure 3 This is a cross-sectional view of the front end portion of the chuck showing a state in which the head of the screw is held by the holding surface of the chuck.

[0017] Description of Reference Numerals

[0018] 10 Screw tightening machine

[0019] 12 screws

[0020] 14 Head

[0021] 14B outer surface

[0022] 20 guide holes

[0023] 22 Subject

[0024] 24 Chuck

[0025] 26 Fastening rod

[0026] 66 First support point

[0027] 72 first force-applying component

[0028] 90 First holding surface

[0029] 106 Second support point

[0030] 112 second force applying member

[0031] 130 Second holding surface

[0032] 140 Axial DETAILED DESCRIPTION

[0033] Hereinafter, a screw fastening machine 10 according to an embodiment of the present invention will be described with reference to the drawings.

[0034] Figure 1 It is a cross-sectional view showing the screw fastening machine 10 according to the present embodiment. Figure 2It is a cross-sectional view of the front end portion of the chuck 24 showing a state in which the screw 12 is supplied to the chuck 24 . Figure 3 This is a cross-sectional view of the front end portion of the chuck 24 showing a state in which the head portion 14 of the screw 12 is held by the holding surface (90, 130) of the chuck 24. Figure 3 The chuck 24 is shown in a state where it holds the open angle of the head 14 of the screw 12 .

[0035] like Figure 1 As shown, the screw fastening machine 10 is a device that inserts and tightens a screw 12 into a target part. The screw fastening machine 10 is used in an assembly device (not shown), for example, that inserts the screw 12 into a screw hole in a workpiece to perform assembly. The main body 22 of the screw fastening machine 10 is mounted, for example, in a mounting hole 42 of a slide plate 40 that reciprocates between a screw supply device provided in the assembly device and the workpiece.

[0036] The screw 12 is composed of a bolt having a head 14 and a screw portion 16 extending from the head 14 and having a smaller diameter than the head 14. The head 14 is formed in a cylindrical shape. A hexagonal hole 18 is formed on the top surface 14A of the head 14.

[0037] In addition, in this embodiment, although the case where the screw 12 is composed of a bolt is described as an example, the screw 12 is not limited to a bolt. The screw 12 may be, for example, a wood screw that is screwed into and fastened to a target portion.

[0038] In addition, this embodiment uses a screw 12 having a hexagonal hole 18 formed in the head 14 as an example, but this embodiment is not limited to this structure. The screw 12 may also have a "-" or "+" groove formed in the head 14. Furthermore, the shape of the head 14 of the screw 12 is not limited to a cylindrical shape and may also be a hexagonal prism, for example.

[0039] The screw tightening machine 10 includes a main body 22 having a guide hole 20 for guiding a screw 12 supplied from a screw supply device. Furthermore, the screw tightening machine 10 includes a chuck 24 supported by the main body 22, to which the screw 12 is supplied from the guide hole 20, and a front end portion that opens and closes centered around a support point (66, 106) with the main body 22. Furthermore, the screw tightening machine 10 includes a biasing member (72, 112) that applies a force in the closing direction toward the front end portion of the chuck 24. Furthermore, the screw tightening machine 10 includes a tightening rod 26 that pushes the screw 12 in the guide hole 20 into the chuck 24, thereby enabling the head 14 of the screw 12 to be held by the front end portion of the chuck 24.

[0040] (main body)

[0041] The main body 22 includes 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 distal end of the cylindrical portion 30 extends toward the distal ends of the first and second support portions 32, 34. A base portion 36 that protrudes laterally is provided at the base end of the main body 22. The screw fastening machine 10 inserts the main body 22 into and positions the mounting hole 42 of the slide plate 40 of the assembly apparatus, with the base portion 36 supported by the opening edge of the mounting hole 42.

[0042] The guide hole 20 extends from the base end to the tip end of the main body 22. 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 serves as a supply port for the screw 12. The guide hole 20 guides the screw 12 supplied from the supply portion 46 toward the tip end.

[0043] (Chuck)

[0044] 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 .

[0045] In this embodiment, the chuck 24 is described as being composed of a pair of first gripping parts 50 and second gripping parts 52. However, the chuck 24 is not limited to this structure. The chuck 24 may be composed of three or more gripping parts.

[0046] (First grip)

[0047] The first gripping portion 50 includes a first rod portion 60 extending along the cylindrical portion 30 and a first retaining portion 62 provided at a front end of the first rod portion 60 .

[0048] The longitudinal center of the first rod 60 is supported by the first support portion 32 of the main body 22 via the first shaft 64. Thus, the first grip 50 can be tilted about the first support point 66, which is the center of the first support portion 32.

[0049] The first rod portion 60 has a first opposing surface 60A, located on the base portion 36 side of the main body 22 relative to the first support point 66, that faces the cylindrical side surface 30A. The first opposing surface 60A tilts away from the cylindrical side surface 30A as it moves from the first support point 66 toward the base end. Thus, the first rod portion 60 can tilt about the first support point 66 until the first opposing surface 60A contacts the cylindrical side surface 30A.

[0050] The first rod portion 60 has a first spring hole 70 at a base end portion on the base portion 36 side of the main body 22. A first biasing member 72 composed of a coil spring is housed in the first spring hole 70.

[0051] The first rod portion 60 has a first threaded hole 76 at its front end. A first locking screw 78 is screwed into the first threaded hole 76, allowing adjustment of the amount of protrusion of the first locking screw 78 from the first rod portion 60. This allows the first rod portion 60 to tilt about the first support point 66 until the first locking screw 78 contacts the cylindrical side surface 30A.

[0052] The first holding portion 62 is inclined toward the central axis C of the screw fastening machine 10 as the outer surface thereof approaches the front end. In addition, the inner surface of the first holding portion 62 is formed of a curved surface.

[0053] The inner surface of the first retaining portion 62 includes an arcuate first proximal arcuate surface 80 that opposes the cylindrical portion 30 of the main body 22 and prevents interference with the cylindrical portion 30, and a first step portion 82 that extends from the first proximal arcuate surface 80 along the end surface of the cylindrical portion 30. Furthermore, the inner surface of the first retaining portion 62 includes a first proximal tapered surface 84 that inclines toward the central axis C as it moves from the first step portion 82 toward the distal end, and a first distal arcuate surface 86 that extends from the first proximal tapered surface 84 toward the distal end. Furthermore, the inner surface of the first retaining portion 62 includes a first distal tapered surface 88 that inclines toward the central axis C as it moves from the first distal arcuate surface 86 toward the distal end.

[0054] Furthermore, the inner surface of the first holding portion 62 includes a first holding surface 90 extending toward the distal end side from the first distal end side tapered surface 88. The first holding surface 90 is formed of a curved surface.

[0055] (Second grip)

[0056] The second gripping portion 52 includes a second rod portion 100 extending along the cylindrical portion 30 and a second retaining portion 102 provided at a front end of the second rod portion 100 .

[0057] The center portion of the second rod portion 100 in the longitudinal direction is supported by the second support portion 34 of the body 22 via the second shaft portion 104. The second grip portion 52 can be tilted about the second support point 106, which is the center of the second shaft portion 104.

[0058] The second rod portion 100 has a second opposing surface 100A, located on the base portion 36 side of the main body 22 relative to the second support point 106, that faces the cylindrical side surface 30A. The second opposing surface 100A tilts away from the cylindrical side surface 30A as it moves from the second support point 106 toward the base end. Thus, the second rod portion 100 can tilt about the second support point 106 until the second opposing surface 100A contacts the cylindrical side surface 30A.

[0059] The second rod portion 100 has a second spring hole 110 at a base end portion on the base portion 36 side of the main body 22. A second biasing member 112 composed of a coil spring is housed in the second spring hole 110.

[0060] The second rod 100 has a second screw hole 116 at its front end. A second locking screw 118 is screwed into the second screw hole 116, and the amount of protrusion of the second locking screw 118 from the second rod 100 can be adjusted. This allows the second rod 100 to tilt about the second support point 106 until the second locking screw 118 contacts the side surface 30A of the barrel.

[0061] In addition, in this 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 structure. For example, the chuck 24 may be configured so that one of the first gripping portion 50 and the second gripping portion 52 is fixed and the other is tiltable.

[0062] The second holding portion 102 is inclined toward the central axis C of the screw fastening machine 10 as the outer surface thereof approaches the front end. In addition, the inner surface of the second holding portion 102 is formed of a curved surface.

[0063] The inner surface of the second retaining portion 102 includes an arcuate second proximal arcuate surface 120 that opposes the cylindrical portion 30 of the main body 22 and prevents interference with the cylindrical portion 30, and a second step portion 122 that extends from the second proximal arcuate surface 120 along the end surface of the cylindrical portion 30. Furthermore, the inner surface of the second retaining portion 102 includes a second proximal tapered surface 124 that inclines toward the central axis C as it moves from the second step portion 122 toward the distal end, and a second distal arcuate surface 126 that extends from the second proximal tapered surface 124 toward the distal end. Furthermore, the inner surface of the second retaining portion 102 includes a second distal tapered surface 128 that inclines toward the central axis C as it moves from the second distal arcuate surface 126 toward the distal end.

[0064] Furthermore, the inner surface of the second holding portion 102 includes a second holding surface 130 extending toward the distal end side from the second distal end side tapered surface 128. The second holding surface 130 is formed of a curved surface.

[0065] The first holding portion 62 of the first grip 50 and the second holding portion 102 of the second grip 52 constitute the front end portion of the chuck 24 capable of holding the head 14 of the screw 12. The front end portion of the chuck 24 is opened and closed by tilting the first grip 50 around the first support point 66 and the second grip 52 around the second support point 106.

[0066] like Figure 3As shown, the first holding surface 90 of the first holding portion 62 constituting the front end portion 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 in a state where the opening angle of the head 14 of the screw 12 is retained. In addition, the second holding surface 130 of the second holding portion 102 constituting the front end portion 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 in a state where the opening angle of the head 14 of the screw 12 is retained.

[0067] In this embodiment, the head 14 of the screw 12 is cylindrical, and the first retaining surface 90 and the second retaining surface 130 are elliptical in the open state retaining the head 14 of the screw 12. Therefore, when the front end of the chuck 24 retains the head 14 of the screw 12, portions of the first retaining surface 90 and the second retaining surface 130 are in line contact with the outer surface 14B of the head 14 along the axial direction 140 of the screw 12.

[0068] The contact area between each holding surface 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, it can be said that the first holding surface 90 and the second holding surface 130 are in surface contact with the outer surface 14B of the head 14.

[0069] Furthermore, by adjusting the curvature of the first holding surface 90 and the second holding surface 130 , the contact area between the first holding surface 90 and the second holding surface 130 and the outer surface 14B of the head 14 can be expanded in the circumferential direction of the head 14 .

[0070] (Force-applying component)

[0071] like Figure 1 As shown, the first biasing member 72 as a biasing member is arranged in a state compressed between the end surface of the first spring hole 70 and the cylindrical 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 rod portion 60 is away from the cylindrical side surface 30A.

[0072] The second urging member 112 is compressed between the end surface of the second spring hole 110 and the cylindrical side surface 30A. The second urging member 112 urges the second gripping portion 52 of the chuck 24 so that the second facing surface 100A of the second rod 100 moves away from the cylindrical side surface 30A.

[0073] Thus, the first and second urging members 72 and 112 constituting the urging members apply a force in the closing direction to close the distal end portion of the chuck 24 formed by the first holding portion 62 of the first gripping portion 50 and the second holding portion 102 of the second gripping portion 52 .

[0074] (Tightening rod)

[0075] The tightening rod 26 extends from a drive device (not shown) provided above a workpiece placement position of the assembly apparatus. The drive device includes a rotating mechanism for rotating the tightening rod 26 and an elevator for raising and lowering the tightening rod 26 together with the rotating mechanism.

[0076] The tightening rod 26 has an engaging structure in which the front end engages with the head 14 of the screw 12. In this embodiment, which uses a screw 12 having a hexagonal hole 18 in the head 14, the tightening rod 26 is formed into a hexagonal column shape that can fit into the hexagonal hole 18 of the head 14 of the screw 12. The tightening rod 26 rotates and lowers the screw 12 engaged with the front end, thereby screwing the screw 12 into the screw hole of the workpiece and tightening it.

[0077] (Action description)

[0078] When the screw 12 is fastened to the workpiece using the screw fastener 10, the screw feeder of the assembly apparatus feeds the screw 12 from the feed portion 46 of the screw fastener 10 placed on the slide plate 40 into the guide hole 20. The screw 12 is then guided along the guide hole 20 into the chuck 24.

[0079] The head 14 of the screw 12 guided into the chuck 24 is guided toward the center of the chuck 24 along the base end tapered surfaces 84, 124 of the gripping portions 50, 52 constituting the chuck 24. As a result, the screw 12 is temporarily held in the chuck 24 with the head 14 housed inside the front end arcuate surfaces 86, 126 of the holding portions 62, 102 (see FIG. Figure 2 ).

[0080] In this state, the assembling device slides the slide plate 40 to move the screw fastening machine 10 toward the upper portion of the target portion of the workpiece.

[0081] In addition, the assembly device rotates the fastening rod 26 by the driving device and lowers it to insert the fastening rod 26 into the guide hole 20. Then, the front end of the fastening rod 26 is inserted into the hexagonal hole 18 of the head 14 of the screw 12 and engages with the head 14 of the screw 12 (see FIG. Figure 2 ).

[0082] Furthermore, the driving device further lowers the tightening rod 26, causing the lower edge of the head 14 of the screw 12 to abut against the respective front end tapered surfaces 88, 128, thereby expanding the respective holding portions 62, 102. Consequently, the respective holding portions 62, 102 tilt about the respective support points 66, 106, and the chuck 24 moves in the opening direction to open the front end portion.

[0083] Furthermore, 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 held at the front end portion of the chuck 24 by the respective holding surfaces 90, 130 from the side. Figure 3 ).

[0084] At this time, the retaining 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 the screw 12 from tilting. With this tilt suppressed, the screw portion 16 of the screw 12 is aligned with the screw hole of the target part, screwed into the screw hole, and secured to the target part.

[0085] (Function and Effect)

[0086] The main functions and effects of the screw fastening machine 10 configured as above will be comprehensively described.

[0087] (1) The screw tightening machine 10 includes: a main body 22 having a guide hole 20 for guiding a supplied screw 12; a chuck 24 supported by the main body 22, to which the screw 12 is supplied from the guide hole 20, and a front end portion that opens and closes with a support point (66, 106) with the main body 22 as the center. The screw tightening machine 10 includes a force applying member (72, 112) that applies a force in a closing direction to close the front end portion of the chuck 24. The screw tightening machine 10 includes a tightening 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 front end portion of the chuck 24. The front end portion 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 open angle to hold the head 14.

[0088] According to this embodiment, the holding surface (90, 130) of the chuck 24 is parallel to the outer surface 14B of the head 14 of the screw 12 when the opening angle of the head 14 of the screw 12 is maintained. Therefore, the holding surface (90, 130) of the chuck 24 holding the screw 12 is in line contact or surface contact (surface contact) with the outer surface 14B of the head 14 of the screw 12.

[0089] Therefore, compared to a case where the holding surface (90, 130) inclined relative to the outer surface 14B of the head 14 of the screw 12 is in point contact (point contact), the skewness of the held screw 12 is suppressed. As a result, for example, even when a large gap is formed between the countersunk hole and the head 14 of the screw 12, it is possible to suppress fastening errors caused by the skewness of the screw 12 by the screw fastening machine 10, thereby achieving an improvement in the yield rate.

[0090] Furthermore, in this embodiment, the retaining surfaces (90, 130) are in line contact with the outer surface 14B of the head 14 of the screw 12 from all four sides. This allows the screw 12 held by the chuck 24 to be positioned at the center of the chuck 24, improving the accuracy of positioning the screw portion 16 relative to the screw hole. Consequently, the screw fastening machine 10 facilitates alignment of the screw portion 16 relative to the screw hole.

[0091] (2) In the screw fastening machine 10 , the front end portion of the chuck 24 is in line contact with the outer surface 14B of the head portion 14 along the axial direction 140 of the screw 12 while holding the head portion 14 of the screw 12 .

[0092] In this embodiment, the screw 12 is held with the chuck 24 and the outer surface 14B of the head 14 in line contact along the axial direction 140 of the screw 12 , thereby improving the effect of suppressing the distortion of the held screw 12 .

[0093] Furthermore, in this embodiment, in which the screw 12 rotates with the head 14 held by the chuck 24 , the contact resistance during rotation can be suppressed compared to a case in which the chuck 24 and the outer surface 14B of the head 14 are in contact over the entire circumference.

[0094] (3) In the screw tightening machine 10 , the screw 12 is a bolt tightened by the tightening rod 26 engaged with the head 14 .

[0095] In the present embodiment, the screw fastening machine 10 can be used in assembly work using bolts.

[0096] As described above, the embodiments of the present invention have been described. However, the above embodiments merely illustrate a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific structures of the above embodiments.

[0097] In the above embodiment, the case where the screw fastening machine 10 is used in the assembly device is described, but the method of using the screw fastening machine 10 is not limited thereto. For example, the screw fastening machine 10 may be used alone.

Claims

1. A screw fastening machine, characterized in that: have: a main body having a guide hole for guiding a supplied screw; a chuck supported by the main body, to which the screw is supplied through the guide hole, and wherein a front end portion opens and closes with a support point with the main body as a center; a force applying member for applying a force in a closing direction toward the front end portion of the chuck; A tightening rod that pushes the screw in the guide hole into the chuck so that the head of the screw is held by the front end of the chuck. The front end portion of the chuck has a holding surface that is parallel to the outer surface of the head of the screw when the chuck is in a state where the opening angle of the head is retained.

2. The screw fastening machine according to claim 1, wherein: The front end portion of the chuck is in line contact with the outer surface of the head portion along the axial direction of the screw while holding the head portion of the screw.

3. The screw fastening machine according to claim 1 or 2, wherein: The screw is a bolt fastened by the fastening rod engaged with the head.

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