Screw fastening machine

Abstract

The invention provides a screw fastening machine which can restrain the situation that force larger than normal force acts on a chuck. The screw fastening machine is provided with: a main body having a guide hole for guiding a supplied screw; a chuck which is supported by the main body, is supplied with the screw from the guide hole, and is opened and closed at the front end part by taking the supporting point of the chuck and the main body as the center; a biasing member that applies a biasing force in a closing direction in which the tip of the chuck is closed; and a fastening rod which pushes the screw toward the front end of the chuck while opening the chuck in the closed state, and which can form a state in which the head of the screw is held at the front end of the chuck, the urging member having a first urging member and a second urging member, only the first urging member urges the chuck in the closing direction in a region where the opening angle of the chuck opened with the movement of the pushed screw is equal to or less than a predetermined angle, and the first urging member and the second urging member urge the chuck in the closing direction in a region where the opening angle exceeds the predetermined angle.

Description

Technical Field

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

[0002] Patent Document 1 discloses a bolt tightening machine. The bolt tightening machine includes a chuck for clamping a bolt to be tightened.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-113171

[0006] Problems to be solved by the invention

[0007] In the bolt tightening machine of Patent Document 1, a supplied bolt is sometimes clamped by the chuck in a distorted state. In this state, if the socket pushes the bolt out of the chuck, stress concentrates and a larger force than usual acts on the chuck. Summary of the Invention

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress a situation in which a force greater than usual acts on a chuck.

[0009] 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 a 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 a support point with the main body as the center; a force-applying component, which applies a force in a closing direction of the front end of the chuck; a tightening rod, which pushes the screw toward the front end direction of the chuck while opening the chuck in a closed state, and can form a state in which the head of the screw is maintained at the front end of the chuck, the force-applying component having a first force-applying component and a second force-applying component, in an area where the opening angle of the chuck opened by the movement of the pushed screw is less than a specified angle, only the first force-applying component applies force to the chuck in the closing direction, and in an area where the opening angle exceeds the specified angle, the first force-applying component and the second force-applying component apply force to the chuck in the closing direction.

[0010] Effects of the Invention

[0011] According to one embodiment of the present invention, in a region where the chuck's opening angle is below a predetermined angle, only the first force-applying member applies force to the chuck in the closing direction. In a region where the chuck's opening angle exceeds the predetermined angle, both the first and second force-applying members apply force to the chuck in the closing direction. Thus, the force applied to the chuck in the closing direction is greater in the region where the chuck's opening angle exceeds the predetermined angle than in the region where the chuck's opening angle is below the predetermined angle.

[0012] Therefore, even if the screw inserted into the chuck is tilted, the chuck can be prevented from opening beyond a specified angle by utilizing the strong force generated by the first and second force applying members to apply force to the chuck in the closing direction, thereby preventing the screw from tilting in the chuck.

[0013] On the other hand, if the tightening rod forces a screw that is bent in the chuck, the force applied by the tightening rod is input into the chuck via the screw. As a result, the chuck, urged by the first and second force-applying members, opens beyond a predetermined angle, forcing the bent screw out of the chuck.

[0014] Therefore, the screw fastening machine can expand the movable range of the chuck, thereby suppressing the inclination of the screw put into the chuck in normal times and, at the same time, being able to squeeze out the distorted screw when the screw is abnormally distorted.

[0015] Therefore, the screw fastening machine performs normal operation to suppress the tilt of the inserted screw, and even in the event of an abnormality in which the screw is tilted, it is possible to suppress an action on the chuck that is greater than normal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view showing the screw fastening machine according to this embodiment.

[0017] Figure 2 It is a cross-sectional view of the front end portion of the chuck showing a state in which the screw is clamped by the chuck in a distorted state.

[0018] Figure 3 It is a cross-sectional view showing the base end portion of the grip portion.

[0019] Figure 4 It is a cross-sectional view of the front end portion of the chuck showing a state in which the chuck is opened.

[0020] Description of Reference Numerals

[0021] 10 Screw tightening machine

[0022] 12 screws

[0023] 14 Head

[0024] 22 Subject

[0025] 24 Chuck

[0026] 26 Fastening rod

[0027] 50 One side grip

[0028] 52 Other side grip

[0029] 66 One side support point

[0030] 72 first force-applying member on one side

[0031] 106 Support point on the other side

[0032] 112 first force-applying component on the other side

[0033] 214 Second force-applying member on one side

[0034] 216 One side ball component

[0035] 264 The second force applying member on the other side

[0036] 266 Other side ball parts DETAILED DESCRIPTION

[0037] Hereinafter, a screw fastening machine 10 according to an embodiment of the present invention will be described with reference to the drawings.

[0038] Figure 1 It is a cross-sectional view showing the screw fastening machine 10 according to the present embodiment. Figure 2 It is a cross-sectional view of the front end portion of the chuck 24 showing a state in which the screw 12 is clamped by the chuck 24 in a distorted state. Figure 3 This is a cross-sectional view showing the base end portion of the gripping portion (50, 52), and shows the base end portion of one side gripping portion 50 as an example of the gripping portion (50, 52). Figure 4 It is a cross-sectional view of the front end portion of the chuck 24 showing a state in which the chuck 24 is opened.

[0039] like Figure 1 and Figure 2 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] The screw tightening machine 10 includes a main body 22 having a guide hole 20 for guiding a supplied screw 12. The screw tightening machine 10 includes a chuck 24, which is supported by the main body 22 and is supplied with the screw 12 from the guide hole 20. The chuck 24 has a front end that opens and closes centered around a support point (66, 106) with the main body 22. The screw tightening machine 10 includes a biasing member (72, 112, 214, 264) that applies a force in the closing direction toward the front end of the chuck 24. The screw tightening machine 10 includes a tightening rod 26 that simultaneously opens the closed chuck 24 and pushes the screw 12 toward the front end of the chuck 24, thereby maintaining the head 14 of the screw 12 at the front end of the chuck 24.

[0044] (main body)

[0045] The main body 22 includes a cylindrical portion 30 surrounding the guide hole 20, and a one-side support portion 32 and an other-side support portion 34 supporting the chuck 24. The front end of the cylindrical portion 30 extends toward the front ends of the one-side support portion 32 and the other-side support portion 34. The one-side support portion 32 extends toward one side of the cylindrical portion 30. The other-side support portion 34 extends toward the other side of the cylindrical portion 30.

[0046] A base portion 36 that protrudes laterally is provided at the base end of the body 22. A one-side extension piece 37 that extends along the cylindrical portion 30 on the one-side support portion 32 side extends from the base portion 36. Furthermore, a second-side extension piece 38 that extends along the cylindrical portion 30 on the other-side support portion 34 side extends from the base portion 36.

[0047] 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.

[0048] (Chuck)

[0049] The chuck 24 includes a one-side gripping portion 50 and a second-side gripping portion 52 arranged to sandwich the cylindrical portion 30 having the guide hole 20 . Thus, the chuck 24 includes a plurality of gripping portions ( 50 , 52 ) supported by the body 22 and capable of gripping the head 14 of the screw 12 .

[0050] In this embodiment, the chuck 24 is described as being composed of a pair of one-side gripping portion 50 and the other-side gripping portion 52. However, the chuck 24 is not limited to this structure. The chuck 24 may be composed of, for example, three or more gripping portions.

[0051] (One side grip)

[0052] The one-side grip portion 50 includes a one-side rod portion 60 extending along the cylindrical portion 30 and a one-side holding portion 62 provided at the front end of the one-side rod portion 60 .

[0053] The longitudinal center of the one-side rod portion 60 is supported by the one-side support portion 32 of the main body 22 via the one-side shaft portion 64. Thus, the one-side grip portion 50 can be tilted about the one-side support point 66, which is the center of the one-side support portion 32.

[0054] The side rod portion 60 has a side facing surface 60A that faces the cylindrical side surface 30A, located closer to the base 36 of the main body 22 than the side support point 66. The side facing surface 60A tilts away from the cylindrical side surface 30A as it moves from the side support point 66 toward the base end. Thus, the side rod portion 60 can tilt around the side support point 66 until the side facing surface 60A contacts the cylindrical side surface 30A.

[0055] (First force-applying member on one side)

[0056] The one-side lever portion 60 has a one-side spring hole 70 at its base end portion on the base portion 36 side of the main body 22. A one-side first urging member 72 composed of a coil spring is accommodated in the one-side spring hole 70. The one-side first urging member 72 constitutes one of a plurality of pairs of first urging members (72, 112).

[0057] (Second force-applying member on one side)

[0058] A bottomed mounting hole 200 opening toward the side of the rod 60 is formed in the portion of the one side extension piece 37 facing the one side outer surface 60B of the one side rod 60. The one side mounting hole 200 is inclined toward the front end of the screw fastening machine 10 from the bottom toward the opening.

[0059] A ball plug 210 is mounted in the one-side mounting hole 200. For example, when using a ball plug 210 having an external thread formed on the outer circumference, an internal thread is formed on the inner circumference of the one-side mounting hole 200. The ball plug 210 is screwed into the one-side mounting hole 200 to be mounted in the one-side mounting hole 200.

[0060] The one-side ball plunger 210 includes a one-side housing 212 formed in a bottomed cylindrical shape, a one-side second urging member 214 composed of a coil spring in the one-side housing 212 , and a spherical one-side ball member 216 urged by the one-side second urging member 214 .

[0061] The ball member 216 is urged in the protruding direction. The ball member 216 can contact a portion of the outer surface 60B of the rod portion 60 closer to the distal end than the support point 66. The second biasing member 214 applies a force to the chuck 24 via the ball member 216. Furthermore, the ball member 216 can retract into the housing 212, allowing the rod portion 60 to tilt.

[0062] When the chuck 24 is in the closed position, the ball member 216 of the ball plunger 210 is spaced apart from the outer surface 60B of the rod portion 60 in the grip 50. At an open angle with the head 14 of the screw 12 held at the front end of the chuck 24, the ball member 216 of the ball plunger 210 is in contact with the outer surface 60B of the rod portion 60 in the grip 50.

[0063] When the chuck 24 is further opened from the state in which it is in contact with the outer surface 60B of the rod 60, the ball member 216 of the ball plunger 210 retracts while rolling along the outer surface 60B of the rod 60. The ball member 216 of the ball plunger 210 retracts to an opening angle at which the screw 12 tilted in the chuck 24 can be squeezed out of the chuck 24 by the tightening rod 26.

[0064] The side rod portion 60 has a side screw hole 76 at its front end. A side set screw 78 is screwed into the side screw hole 76, allowing adjustment of the amount of protrusion of the side set screw 78 from the side rod portion 60. This allows the side rod portion 60 to tilt about the side support point 66 until it reaches a closed position, where the side set screw 78 contacts the side surface 30A of the cylinder.

[0065] (One side holding part)

[0066] The one-side holding portion 62 is inclined toward the central axis C of the screw fastening machine 10 as the outer surface thereof goes toward the front end. The inner surface of the one-side holding portion 62 is formed of an elliptical arc-shaped curved surface.

[0067] The inner surface of the one-side retaining portion 62 has an arc-shaped one-side surrounding surface 80 that faces the cylindrical portion 30 of the main body 22 and suppresses interference with the cylindrical portion 30 , and a one-side step portion 82 that extends from the one-side surrounding surface 80 and extends along the end surface of the cylindrical portion 30 in a closed state.

[0068] The inner surface of the one-side holding portion 62 includes a one-side guide surface 84 that tilts toward the central axis C as it moves from the one-side step portion 82 toward the distal end, and a one-side arcuate surface 86 that extends toward the distal end from the one-side guide surface 84. Furthermore, the inner surface of the one-side holding portion 62 includes a one-side inclined surface 88 that tilts toward the central axis C as it moves from the one-side arcuate surface 86 toward the distal end.

[0069] (Handle on the other side)

[0070] The other-side grip portion 52 includes a other-side rod portion 100 extending along the cylindrical portion 30 and a other-side holding portion 102 provided at the front end of the other-side rod portion 100 .

[0071] The longitudinal center of the other side rod portion 100 is supported by the other side support portion 34 of the body 22 via the other side shaft portion 104. The other side grip portion 52 can be tilted about the other side support point 106, which is the center of the other side shaft portion 104.

[0072] The other-side rod portion 100 has a second-side opposing surface 100A, which opposes the cylindrical side surface 30A, on the base 36 side of the main body 22 relative to the second-side support point 106. The second-side opposing surface 100A tilts away from the cylindrical side surface 30A as it moves from the second-side support point 106 toward the base end. Thus, the other-side rod portion 100 can tilt around the second-side support point 106 until the second-side opposing surface 100A contacts the cylindrical side surface 30A.

[0073] (First force-applying member on the other side)

[0074] The other-side rod portion 100 has a second-side spring hole 110 at its base end portion on the base portion 36 side of the main body 22. A second-side first urging member 112 composed of a coil spring is accommodated in the second-side spring hole 110. The second-side first urging member 112 constitutes the other of the plurality of pairs of first urging members (72, 112).

[0075] (Second force-applying member on the other side)

[0076] A bottomed mounting hole 250 opening toward the other side rod 100 is formed on the other side extension piece 38 at a portion facing the other side outer surface 100B of the other side rod 100. The other side mounting hole 250 is inclined toward the front end of the screw fastening machine 10 from the bottom toward the opening.

[0077] The other-side ball plug 260 is mounted in the other-side mounting hole 250. For example, when using the other-side ball plug 260 having external threads formed on the outer circumference, the inner circumference of the other-side mounting hole 250 is formed with internal threads. Then, the other-side ball plug 260 is screwed into the other-side mounting hole 250 to be mounted in the other-side mounting hole 250.

[0078] The other side ball plunger 260 includes a bottomed cylindrical other side housing 262 , a second biasing member 264 composed of a coil spring in the other side housing 262 , and a spherical other side ball member 266 biased by the second biasing member 264 .

[0079] The other-side ball member 266 is urged in the protruding direction. The other-side ball member 266 can abut against a portion of the other-side outer surface 100B of the other-side rod portion 100 closer to the front end than the other-side support point 106, and the other-side second force-applying member 264 applies a force to the chuck 24 via the other-side ball member 266. Furthermore, the other-side ball member 266 can retract into the other-side housing 262, allowing the other-side rod portion 100 to tilt.

[0080] When the chuck 24 is in the closed position, the other-side ball member 266 of the other-side ball plunger 260 is away from the other-side outer surface 100B of the other-side rod portion 100 in the other-side grip 52. At the open angle in which the head 14 of the screw 12 is held at the front end of the chuck 24, the other-side ball member 266 of the other-side ball plunger 260 contacts the other-side outer surface 100B of the other-side rod portion 100 in the other-side grip 52.

[0081] When the chuck 24 is further opened from the state in which it is in contact with the other outer surface 100B of the other rod 100, the other ball member 266 of the other ball plunger 260 retracts while rolling along the other outer surface 100B of the other rod 100. The other ball member 266 of the other ball plunger 260 retracts to an opening angle at which the screw 12 tilted in the chuck 24 can be squeezed out of the chuck 24 by the tightening rod 26.

[0082] The other-side rod 100 has a second-side screw hole 116 at its front end. A second-side set screw 118 is screwed into the second-side screw hole 116, allowing adjustment of the amount by which the second-side set screw 118 protrudes from the other-side rod 100. This allows the other-side rod 100 to tilt about the second-side support point 106 until it reaches a closed position, where the second-side set screw 118 contacts the cylindrical side surface 30A.

[0083] In addition, in this embodiment, both the one-side gripping portion 50 and the other-side 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 have one of the one-side gripping portion 50 and the other-side gripping portion 52 fixed and the other configured to be tiltable.

[0084] (Other side holding part)

[0085] The other-side 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. The inner surface of the other-side holding portion 102 is formed of an elliptical arc-shaped curved surface.

[0086] The inner surface of the other side retaining portion 102 has an arc-shaped other side surrounding surface 120 that is opposite to the cylindrical portion 30 of the main body 22 and suppresses interference with the cylindrical portion 30, and an other side step portion 122 that extends from the other side surrounding surface 120 and extends along the end surface of the cylindrical portion 30 in a closed state.

[0087] The inner surface of the other-side holding portion 102 includes a second-side guide surface 124 that tilts toward the central axis C as it moves from the second-side step 122 toward the distal end, and a second-side arcuate surface 126 that extends from the second-side guide surface 124 toward the distal end. Furthermore, the inner surface of the other-side holding portion 102 includes a second-side inclined surface 128 that tilts toward the central axis C as it moves from the second-side arcuate surface 126 toward the distal end.

[0088] (Opening and closing action)

[0089] The one side holding portion 62 of the one side grip 50 and the other side holding portion 102 of the other side 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 one side grip 50 around the one side support point 66 and tilting the other side grip 52 around the other side support point 106.

[0090] The chuck 24 is in a closed state in which the gripping portions 50 , 52 are tilted until the gripping portions 50 , 52 are biased by the first biasing members 72 , 112 and the set screws 78 , 118 are in contact with the cylindrical side surface 30A.

[0091] In addition, the chuck 24 is formed in an open state in which the gripping portions 50, 52 are tilted to form an open state in which the head portion 14 of the screw 12 is held at an opening angle by the front end portion of each inclined surface 88, 128 of each holding portion 62, 102 (see FIG. Figure 1 ).

[0092] Furthermore, the chuck 24 is formed in a fully opened state in which the gripping portions 50, 52 are tilted to an opening angle at which the opposing surfaces 60A, 100A of the rod portions 60, 100 are in contact with the side surface 30A of the cylindrical portion (see FIG. Figure 2 ).

[0093] like Figure 3 As shown, in the screw fastening machine 10, each opposing surface 60A (100A) of each rod portion 60 (100) of each holding portion 50 (52) constituting the chuck 24 is inclined at an inclination angle α relative to each inner side surface 60C (100C) of each rod portion 60 (100). Figure 3 In the figure, only one gripping portion 50 is shown as an example of a gripping portion.

[0094] like Figures 2 to 4 As shown, the inclination angle α is set so that in the fully opened state (refer to Figure 2 and Figure 4 ), the separation distance D of each inclined surface 88 (128) is longer than the longest distance L of the longest horizontal length of the screw 12 tilted in the chuck 24 (refer to Figure 4 ).

[0095] (Force-applying component)

[0096] like Figure 1 As shown, the first biasing member 72, which serves as the first biasing member, is arranged compressed between the end surface of the spring hole 70 of the gripping portion 50 and the cylindrical side surface 30A of the main body 22. The first biasing member 72 biases the gripping portion 50 of the chuck 24 so that the facing surface 60A of the rod 60 is away from the cylindrical side surface 30A.

[0097] The other-side first urging member 112 constituting the first urging member is arranged in a state compressed between the end surface of the other-side spring hole 110 of the other-side gripping portion 52 and the cylindrical side surface 30A of the main body 22. The other-side first urging member 112 urges the other-side gripping portion 52 of the chuck 24 such that the other-side facing surface 100A of the other-side rod portion 100 moves away from the cylindrical side surface 30A.

[0098] Thus, the first biasing member 72 on one side and the first biasing member 112 on the other side apply a force in the closing direction to close the front end portion of the chuck 24 formed by the one holding portion 62 of the one gripping portion 50 and the other holding portion 102 of the other gripping portion 52 .

[0099] A second biasing member 214, serving as a second biasing member, is disposed between the bottom surface of a housing 212 of the ball plunger 210 provided on the extension piece 37 of the main body 22 and an outer surface 60B of the grip 50. The second biasing member 214 can bias the outer surface 60B of the rod 60 via the ball member 216 of the ball plunger 210.

[0100] The second biasing member 264, serving as a second biasing member, is disposed between the bottom surface of the other-side housing 262 of the other-side ball plunger 260 provided on the other-side extension piece 38 of the main body 22 and the other-side outer surface 100B of the other-side grip 52. The second biasing member 264 can bias the other-side outer surface 100B of the other-side rod 100 via the other-side ball member 266 of the other-side ball plunger 260.

[0101] When the ball members 216 and 266 are in contact with the outer surfaces 60B and 100B of the rods 60 and 100 , the second biasing member 214 and the second biasing member 264 constituting the second biasing member apply a force to the chuck 24 in the closing direction to close the front end portion of the chuck 24 .

[0102] In the region where the opening angle of the chuck 24 opened by the movement of the screw 12 pushed by the tightening rod 26 is less than a predetermined angle, only the first force applying members 72, 112 apply force to the chuck 24 in the closing direction. In the region where the opening angle exceeds the predetermined angle, the first force applying members 72, 112 and the second force applying members 214, 264 apply force to the chuck 24 in the closing direction (for example, see Figure 2 ).

[0103] Here, the predetermined angle is the opening angle in a state where the head 14 of the screw 12 is held at the front end of the chuck 24 (see Figure 1 ).

[0104] In the present embodiment, the opening angle in the state where the head 14 of the screw 12 is held by the front end portion of the chuck 24 is set to a predetermined angle, but the predetermined angle is not limited to this angle.

[0105] The specified angle can also be, for example, an opening angle smaller than the opening angle of the chuck 24 at the front end portion where the head 14 of the screw 12 is held. In this case, the force in the closing direction can be increased before the head 14 of the screw 12 is held by the front end portion of the chuck 24.

[0106] The spring constants of the first force application member 72 on one side and the first force application member 112 on the other side are substantially the same. The spring constants of the second force application member 214 on one side and the second force application member 264 on the other side are substantially the same. Furthermore, the spring constants of the second force application members 214 and 264 are greater than the spring constants of the first force application members 72 and 112, respectively. The applied force of the second force application members 214 and 264 is greater than the applied force of the first force application members 72 and 112, respectively.

[0107] (Tightening rod)

[0108] 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.

[0109] 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.

[0110] (Action description)

[0111] When the screw fastener 10 is used to fasten the screw 12 to the workpiece, 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 .

[0112] The head 14 of the screw 12 guided into the chuck 24 is guided toward the center of the chuck 24 along the guide 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 (not shown) with the head 14 accommodated within the arcuate surfaces 86, 126 of the retaining portions 62, 102.

[0113] 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.

[0114] The assembly device rotates and lowers the fastening rod 26 by the driving device to insert the fastening rod 26 into the guide hole 20. Then, the front end of the fastening rod 26 is engaged with the head 14 of the screw 12 while being inserted into the hexagonal hole 18 of the head 14 of the screw 12.

[0115] Furthermore, the driving device further lowers the tightening rod 26, causing the lower edge of the head 14 of the screw 12 to contact the inclined surfaces 88, 128, thereby expanding the holding portions 62, 102. Thus, the holding portions 62, 102 tilt about the supporting points 66, 106, and the chuck 24 moves in the opening direction to open the front end portion.

[0116] The screw 12 is held at the front end of the chuck 24 with the outer surface 14B of the head 14 being clamped from the side by the inclined surfaces 88 , 128 when the head 14 reaches the front ends of the inclined surfaces 88 , 128 of the holding portions 62 , 102 .

[0117] In this state, the screw portion 16 of the screw 12 is aligned with the screw hole of the target portion and then screwed into the screw hole to be fastened to the target portion.

[0118] (Function and Effect)

[0119] The main functions and effects of the screw fastening machine 10 configured as above will be comprehensively described.

[0120] (1) The screw tightening machine 10 includes a main body 22 having a guide hole 20 for guiding a supplied screw 12. The screw tightening machine 10 includes a chuck 24, which is supported by the main body 22, is supplied with the screw 12 from the guide hole 20, and has a front end 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, 214, 264) that applies a force in a closing direction toward the front end of the chuck 24. The screw tightening machine 10 includes a tightening rod 26 that pushes the screw 12 toward the front end of the chuck 24 while opening the closed chuck 24, and can form a state in which the head 14 of the screw 12 is held at the front end of the chuck 24. The force applying member (72, 112, 214, 264) includes a first force applying member (72, 112) and a second force applying member (214, 264). In a region where the opening angle of the chuck 24 opened by the movement of the pushed screw 12 is less than a predetermined angle, only the first force applying member (72, 112) applies force to the chuck 24 in the closing direction. In a region where the opening angle exceeds the predetermined angle, the first force applying member (72, 112) and the second force applying member (214, 264) apply force to the chuck 24 in the closing direction.

[0121] According to this embodiment, in an area where the opening angle of the chuck 24 is less than or equal to a predetermined angle, only the first force applying member (72, 112) applies force to the chuck 24 in the closing direction. Furthermore, in an area where the opening angle exceeds the predetermined angle, both the first force applying member (72, 112) and the second force applying member (214, 264) apply force to the chuck 24 in the closing direction. As a result, the force applied to the chuck 24 in the closing direction is greater in the area where the opening angle exceeds the predetermined angle than in the area where the opening angle is less than or equal to the predetermined angle.

[0122] Therefore, even if the screw 12 inserted into the chuck 24 is tilted, the screw fastening machine 10 can use the strong force obtained by adding the force of the first force applying member (72, 112) to the force of the second force applying member (214, 264) to force the chuck 24 in the closing direction. As a result, the screw fastening machine 10 prevents the chuck 24 from opening beyond a predetermined angle, and prevents the screw 12 from tilting in the chuck 24 before it occurs.

[0123] On the other hand, when the tightening rod 26 pushes out the screw 12 that is tilted in the chuck 24, the force applied by the tightening rod 26 is input to the chuck 24 via the screw 12. As a result, the chuck 24, which is biased by the first biasing member (72, 112) and the second biasing member (214, 264), opens beyond a predetermined angle, and the tilted screw 12 is pushed out of the chuck 24.

[0124] Therefore, the screw fastening machine 10 can expand the movable range of the chuck 24 so as to suppress the screw 12 introduced into the chuck 24 from tilting under normal circumstances and to squeeze out the tilted screw 12 when the screw 12 is abnormally tilted.

[0125] Therefore, the screw fastening machine 10 performs normal operation to suppress the tilt of the inserted screw 12 , and can suppress a force greater than normal from acting on the chuck 24 even in an abnormal situation where the screw 12 is tilted.

[0126] This suppresses the need to replace the chuck 24 that receives a force greater than normal or the need to stop the production line due to the replacement work, thereby improving production efficiency.

[0127] Here, when a single force-applying member with a small force is applied to the entire opening angle to squeeze out the skewed screw 12, it is difficult to correct the tilt of the inserted screw 12. In addition, the head 14 of the screw 12 cannot be held by the front end of the chuck 24, and the screw 12 may fall.

[0128] On the other hand, if a single force-applying member with a large force is used to apply force over the entire opening angle to the point where the distorted screw 12 can be squeezed out, the frictional resistance between the screw 12 and the chuck 24 in contact with the screw 12 increases. This requires increasing the force exerted on the screw 12 by the chuck 24 and the rotational force required to rotate the screw 12, which increases the size of the drive device.

[0129] On the other hand, the screw fastening machine 10 of the present embodiment has a function of correcting the inclination of the inserted screw 12 and can also achieve miniaturization of the driving device for rotating and raising / lowering the fastening rod 26 .

[0130] (2) In the screw fastening machine 10 , the predetermined angle is the opening angle in a state where the head 14 of the screw 12 is held at the front end portion of the chuck 24 .

[0131] In this embodiment, when the opening angle of the chuck 24 is larger than the opening angle when the head 14 of the screw 12 is held at the tip of the chuck 24 , the force of the screw tightening machine 10 urging the chuck 24 in the closing direction increases.

[0132] Therefore, compared with the case where the force in the closing direction becomes larger at an opening angle larger than the opening angle at which the head 14 of the screw 12 is held in the chuck 24, the tilt suppression effect of the inserted screw 12 or the falling prevention effect of the screw 12 can be improved.

[0133] Furthermore, compared to a case where the force in the closing direction increases at an opening angle smaller than the opening angle at which the head 14 of the screw 12 is held in the chuck 24 , the frictional resistance generated when the screw 12 is fed out of the chuck 24 during tightening can be reduced.

[0134] (3) In the screw fastening machine 10 , the second biasing member ( 214 , 264 ) applies a biasing force to the chuck 24 via the ball member ( 216 , 266 ).

[0135] In this embodiment, the frictional resistance generated between the chuck 24 and the ball member (216, 266) in contact with the chuck 24 is suppressed. As a result, the chuck 24 can perform a smooth opening and closing operation.

[0136] (4) In the screw fastening machine 10, the force applied by the second force applying member (214, 264) is greater than the force applied by the first force applying member (72, 112).

[0137] In this embodiment, the change in the force in the closing direction generated when the opening angle of the chuck 24 exceeds a predetermined angle increases. As a result, the screw fastening machine 10 can improve the effect of suppressing the distortion of the screw 12 inserted into the chuck 24.

[0138] (5) In the screw fastening machine 10, the chuck 24 includes a plurality of gripping portions (50, 52) supported by the main body 22 and capable of gripping the head portion 14 of the screw 12. The force applying member (72, 112, 214, 264) includes a first force applying member (72, 112) and a second force applying member (214, 264) disposed between the main body 22 and each gripping portion (50, 52).

[0139] This embodiment can hold the screw 12 in a state of being clamped by a plurality of gripping portions (50, 52) and a first urging member (72, 112) and a second urging member (214, 264) disposed between the gripping portions (50, 52).

[0140] Thus, since the tightened screw 12 can be held at the center position, tightening errors can be suppressed.

[0141] 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.

[0142] 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, which pushes the screw toward the front end of the chuck while opening the chuck in the closed state, so that the head of the screw is retained at the front end of the chuck. The force applying member includes a first force applying member and a second force applying member. In a region where the opening angle of the chuck opened by the movement of the pushed screw is less than a predetermined angle, only the first biasing member biases the chuck in the closing direction. In a region where the opening angle exceeds the predetermined angle, the first and second urging members urge the chuck in the closing direction.

2. The screw fastening machine according to claim 1, wherein: The predetermined angle is the opening angle in a state in which the head of the screw is held at the front end portion of the chuck.

3. The screw fastening machine according to claim 1 or 2, wherein: The second biasing member applies a biasing force to the chuck via a ball member.

4. The screw fastening machine according to claim 1 or 2, wherein: The urging force of the second urging member is greater than the urging force of the first urging member.

5. The screw fastening machine according to claim 1, wherein: The chuck has a plurality of gripping portions supported by the main body and capable of gripping the head of the screw. The urging member includes the first urging member and the second urging member disposed between the main body and each of the grips.

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