Fastening tool

Abstract

To provide a fastening tool capable of suppressing reaction force of force for pushing a fastening object via a screw by a driver bit moving in the axial direction, when a load is high when boring a hole in the fastening object by the screw.SOLUTION: A fastening tool 1 includes a bit holding part 3 that holds a driver bit 2 engageable with a screw and is rotatable in a circumferential direction of the driver bit 2 and movable in an axial direction of the driver bit 2, a bit rotation motor 40 that rotates the bit holding part 3, a bit movement motor 50 that moves the bit holding part 3 in the axial direction, and a control unit 100 that controls a rotation speed of the bit holding part 3 via the bit rotation motor 40 and controls a movement speed of the bit holding part 3 by controlling output of the bit movement motor 50. The control part 100 detects the state of the bit rotation motor 40 and controls the moving speed of the bit holding part 3 based on the state of the bit rotation motor 40 when the screw engaged with the driver bit 2 is fastened to the object to be fastened.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a fastening tool in which a driver bit is engaged with a screw, the screw is pressed against an object to be fastened by the driver bit, and the driver bit is rotated to screw in the screw. [Background technology]

[0002] A portable tool known as a driving machine is known that uses the air pressure of compressed air supplied from an air compressor or the combustion pressure of gas to drive connecting fasteners loaded in a magazine one after another from the tip of a driver guide.

[0003] In the past, a pneumatic screw driver has been proposed as a tool that rotates a bit to tighten a screw and moves the bit in the direction of driving the screw, using an air motor to rotate the bit and air pressure to move it in the direction of driving the screw (see, for example, Patent Document 1).

[0004] Also, a screw driver has been proposed in which a spring is compressed by the driving force of a motor that rotates a driver bit, and the driver bit is moved axially by the bias of the spring to drive the screw (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5262461 [Patent Document 2] Patent No. 6197547 Summary of the Invention [Problem to be solved by the invention]

[0006] One task using a screw driver is to drive screws into a component with a gypsum board placed on a steel plate substrate. However, with a configuration in which the driver bit is moved axially by the bias of a spring to drive the screw, it is difficult to control the movement speed of the bit holder. For example, even when the spring bias is not enough to drive the screw into the steel plate, the driver bit continues to move forward due to the bias of the spring, and the force of the driver bit pushing the object to be fastened via the screw causes the fastening tool to float up.

[0007] The present invention has been made to solve the above problems, and has an object to provide a fastening tool that allows the moving speed of the bit holding portion to be controlled. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a fastening tool comprising: a bit holding portion that holds a driver bit that can be engaged with a screw and that is rotatable in the circumferential direction of the driver bit and movable in the axial direction; a first motor that rotates the bit holding portion; a second motor that moves the bit holding portion axially; a control portion that controls the rotational speed of the bit holding portion via the first motor and controls the movement speed of the bit holding portion by controlling the output of the second motor; and a first motor state detection portion that detects the state of the first motor, wherein the control portion controls the movement speed of the bit holding portion based on the state of the first motor when a screw engaged with the driver bit is fastened into an object to be fastened.

[0009] In the present invention, the moving speed of the bit holding portion is controlled based on the state of the first motor when the screw engaged with the driver bit is fastened into the object to be fastened. [Effects of the Invention]

[0010] In the present invention, the moving speed of the bit holder can be controlled based on the state of the first motor that rotates the bit holder. [Brief explanation of the drawings]

[0011] [Figure 1A] FIG. 2 is a side cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. [Figure 1B] FIG. 2 is a top cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. [Figure 1C] FIG. 2 is an exploded perspective view showing an example of the internal structure of the fastening tool of the present embodiment. [Figure 2A] 1 is a perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; [Figure 2B] 1 is a perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; [Figure 3A] 1 is a cross-sectional perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; [Figure 3B] 1 is a cross-sectional perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; [Figure 4] FIG. 2 is a perspective view showing an example of a screw feed portion and a nose portion of the present embodiment. [Figure 5] 1 is a block diagram showing an example of a fastening tool according to an embodiment of the present invention; [Figure 6] FIG. 2 is a perspective view illustrating an example of a setting unit. [Figure 7A] 4 is a flowchart showing an example of an operation of the fastening tool according to the present embodiment. [Figure 7B] 4 is a flowchart showing an example of an operation of the fastening tool according to the present embodiment. [Figure 8A] 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor. [Figure 8B] 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor. [Figure 9A] FIG. 4 is a cross-sectional view showing a fastened state of the screw. [Figure 9B] FIG. 4 is a cross-sectional view showing a fastened state of the screw. [Figure 9C] FIG. 4 is a cross-sectional view showing a fastened state of the screw. [Figure 10A] 10 is a flowchart showing another example of the operation of the fastening tool according to the present embodiment. [Figure 10B]10 is a flowchart showing another example of the operation of the fastening tool according to the present embodiment. [Figure 11A] 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor. [Figure 11B] 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor. [Figure 11C] 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor. [Figure 12A] 10 is a flowchart showing another example of the operation of the fastening tool according to the present embodiment. [Figure 12B] 10 is a flowchart showing another example of the operation of the fastening tool according to the present embodiment. [Figure 13] 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the fastening tool of the present invention will be described with reference to the drawings.

[0013] <Configuration example of fastening tool according to this embodiment> FIG. 1A is a side cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment, FIG. 1B is a top cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment, and FIG. 1C is an exploded oblique view showing an example of the internal structure of the fastening tool of the present embodiment.

[0014] The fastening tool 1 of this embodiment includes a bit holding unit 3 that holds a driver bit 2 rotatably and axially movable, a first drive unit 4 that rotates the driver bit 2 held by the bit holding unit 3, and a second drive unit 5 that moves the driver bit 2 held by the bit holding unit 3 in the axial direction.

[0015] The fastening tool 1 also includes a screw storage section 6 in which the screw 200 is stored, a screw feed section 7 (described later) that feeds the screw stored in the screw storage section 6, and a nose section 8 that is pressed against the object to be fastened and from which the screw 200 is ejected.

[0016] Furthermore, the fastening tool 1 includes a tool body 10 and a handle 11. The fastening tool 1 also includes, at the end of the handle 11, a battery attachment portion 13 to which a battery 12 is detachably attached.

[0017] In the fastening tool 1, the tool body 10 extends in one direction along the axial direction of the driver bit 2 indicated by arrows A1 and A2, and the handle 11 extends in another direction intersecting the extension direction of the tool body 10. In the fastening tool 1, the direction in which the tool body 10 extends, i.e., the axial direction of the driver bit 2 indicated by arrows A1 and A2, is defined as the front-rear direction. In addition, in the fastening tool 1, the direction in which the handle 11 extends is defined as the up-down direction. Furthermore, in the fastening tool 1, the direction perpendicular to the extension direction of the tool body 10 and the extension direction of the handle 11 is defined as the left-right direction.

[0018] The first drive unit 4 is provided on one side of the tool body 10, i.e., the rear side, across the handle 11. The second drive unit 5 is provided on the other side of the tool body 10, i.e., the front side, across the handle 11.

[0019] The screw storage section 6 stores a plurality of screws 200 connected by a connecting band and wound in a spiral shape.

[0020] 2A and 2B are perspective views showing an example of the configuration of the main parts of the fastening tool of this embodiment, and FIGS. 3A and 3B are cross-sectional perspective views showing an example of the configuration of the main parts of the fastening tool of this embodiment. Next, the bit holding unit 3 and the first driving unit 4 will be described with reference to each figure.

[0021] The bit holding portion 3 includes a holding member 30 that detachably holds the driver bit 2, a rotary guide member 31 that supports the holding member 30 so that it can move in the forward and backward directions indicated by arrows A1 and A2 along the axial direction of the driver bit 2 and rotates together with the holding member 30, a moving member 32 that moves the holding member 30 in the forward and backward directions along the rotary guide member 31, and a biasing member 33 that biases the moving member 32 in the backward direction indicated by arrow A2.

[0022] The holding member 30 is configured as, for example, a cylindrical member whose outer diameter is slightly smaller than the inner diameter of the rotation guide member 31 and which can be placed inside the rotation guide member 31. The holding member 30 has an opening 30a at its front end along the axial direction of the driver bit 2, the opening 30a having a shape that matches the cross-sectional shape of the driver bit 2. The holding member 30 is provided with a detachable holding mechanism 30c in the opening 30a that detachably holds the driver bit 2. The opening 30a of the holding member 30 is exposed to the inside of the rotation guide member 31, and the driver bit 2 is detachably inserted into the opening 30a.

[0023] The detachable holding mechanism 30c includes a ball 30d exposed in the opening 30a and a spring 30e that biases the ball 30d in the direction of exposure in the opening 30a. The spring 30e is an annular leaf spring and is fitted around the outer periphery of the holding member 30.

[0024] In the detachable holding mechanism 30c, the ball 30d biased by the spring 30e fits into a groove in the driver bit 2, thereby preventing the driver bit 2 from accidentally coming out of the holding member 30. Furthermore, when a force of a predetermined magnitude or greater is applied in a direction in which the driver bit 2 is removed from the holding member 30, the ball 30d retracts while deforming the annular spring 30e, allowing the driver bit 2 to be removed from the holding member 30.

[0025] The rotation guide member 31 extends in the extension direction of the tool body 10, i.e., in the front-to-rear direction indicated by arrows A1 and A2 along the axial direction of the driver bit 2. The rotation guide member 31 has a cylindrical shape inside which the holding member 30 fits, and its front end is rotatably supported via a bearing 34a, which is an example of a bearing, on a front frame 10b provided on the front side of a case 10a that forms the exterior of the tool body 10. In addition, the rotation guide member 31 has its rear end connected to the first drive unit 4.

[0026] The rotation guide member 31 has grooves 31a formed at two radially opposing locations on its peripheral surface, the grooves 31a extending in the front-to-rear direction indicated by arrows A1 and A2 along the axial direction of the driver bit 2. The rotation guide member 31 penetrates the holding member 30 in the radial direction, and connecting members 30b protruding from both sides of the holding member 30 enter the grooves 31a, thereby connecting the rotation guide member 31 to the holding member 30 via the connecting members 30b.

[0027] The connecting member 30b is composed of a cylindrical member with an oval cross section, and the longitudinal direction of the oval shape is oriented along the extension direction of the groove 31a, which is parallel to the axial direction of the driver bit 2, as indicated by arrows A1 and A2. The lateral direction of the oval shape of the connecting member 30b is oriented perpendicular to the extension direction of the groove 31a, as indicated by arrows B1 and B2, i.e., along the rotation direction of the rotation guide member 31. The width of the oval shape of the connecting member 30b in the lateral direction, i.e., the width along the rotation direction of the rotation guide member 31, is configured to be slightly smaller than the width of the groove 31a along the same direction.

[0028] As a result, the connecting member 30b inserted in the groove 31a is supported in the groove 31a so as to be movable along the axial direction of the rotation guide member 31. Furthermore, the movement of the connecting member 30b in the rotational direction relative to the rotation guide member 31 is restricted between one side surface and the other side surface of the groove 31a that are aligned along the extension direction of the groove 31a. Therefore, as the rotation guide member 31 rotates, the connecting member 30b is pressed against one side surface or the other side surface of the groove 31a depending on the rotational direction of the rotation guide member 31, and receives a force from the rotation guide member 31 in the circumferential direction, which is the rotational direction.

[0029] Therefore, when the rotation guide member 31 rotates, the connecting member 30b is pressed into the groove portion 31a of the rotation guide member 31, causing the holding member 30 to rotate together with the rotation guide member 31. Furthermore, the connecting member 30b is guided by the groove portion 31a of the rotation guide member 31, and the holding member 30 moves in the front-to-rear direction along the axial direction of the driver bit 2.

[0030] The moving member 32 includes a first moving member 32a that rotates together with the holding member 30 and moves the holding member 30 in the forward and backward directions along the rotation guide member 31, a second moving member 32c that is supported by the first moving member 32a via a bearing 32b and pushes the first moving member 32a via the bearing 32b, and a buffer member 32d that is attached to the rear side of the second moving member 32c.

[0031] The first moving member 32a has an inner diameter slightly larger than the outer diameter of the rotation guide member 31 and is configured as, for example, a cylindrical member that is placed on the outside of the rotation guide member 31. The first moving member 32a is connected to the holding member 30 via a connecting member 30b that protrudes from a groove portion 31a of the rotation guide member 31, and is supported so as to be movable along the axial direction of the rotation guide member 31.

[0032] Bearing 32b is an example of a bearing, and is inserted between the outer periphery of first moving member 32a and the inner periphery of second moving member 32c. First moving member 32a constitutes a bearing inner ring holding member that holds the inner ring of bearing 32b, and second moving member 32c constitutes a bearing outer ring holding member that holds the outer ring of bearing 32b. The inner ring of bearing 32b is supported on the outer periphery of first moving member 32a so as to be immovable in both the rotational and axial directions, and the outer ring is supported on the inner periphery of second moving member 32c so as to be immovable in both the rotational and axial directions.

[0033] As a result, the second moving member 32c is connected to the first moving member 32a via the bearing 32b in a state where movement in the front-to-rear direction along the axial direction is restricted. Also, the second moving member 32c rotatably supports the first moving member 32a via the bearing 32b.

[0034] Therefore, as the second moving member 32c moves back and forth along the axial direction, the first moving member 32a is pushed by the second moving member 32c via the bearing 32b, and moves back and forth along the axial direction together with the second moving member 32c. In addition, the first moving member 32a is rotatable relative to the second moving member 32c, which is non-rotatable relative to the rotation guide member 31.

[0035] The biasing member 33, in this example, is formed by a coil spring and is placed outside the rotation guide member 31 between the front frame 10b, which is provided on the front side of the case 10a of the tool body 10, and the second moving member 32c of the moving member 32, and abuts against a spring seat 32f that is arranged so as to contact the end face of the outer ring of the bearing 32b. The biasing member 33 is compressed when the moving member 32 moves forward as indicated by arrow A1, and applies a force to the moving member 32 that pushes the moving member 32 backward as indicated by arrow A2.

[0036] The first drive unit 4 includes a bit rotation motor 40 driven by electricity supplied from the battery 12, and a reducer 41. The bit rotation motor 40 is an example of a first motor, and a shaft 40a of the bit rotation motor 40 is connected to the reducer 41, and a shaft 41a of the reducer 41 is connected to the rotation guide member 31. In the first drive unit 4, the reducer 41 is configured using a planetary gear, and the bit rotation motor 40 is arranged coaxially with the rotation guide member 31, the holding member 30, and the driver bit 2 held by the holding member 30.

[0037] The first drive unit 4 has a bit rotation motor 40 and a reducer 41 attached to a rear frame 10c provided on the rear side of the case 10a of the tool body 10, and a shaft 41a of the reducer 41 is supported by the rear frame 10c via a bearing 42. The rear end of the rotation guide member 31 is connected to the shaft 41a of the reducer 41, and the shaft 41a is supported by the rear frame 10c via the bearing 42, so that the rotation guide member 31 is rotatably supported via the bearing 42, which is an example of a bearing.

[0038] The bit holding unit 3 and the first drive unit 4 are assembled together by connecting the front frame 10b and the rear frame 10c with a connecting member 10d extending in the front-to-rear direction, and the front frame 10b is fixed to the case 10a of the tool body 10 with screws 10e.

[0039] Furthermore, the front end of the rotation guide member 31 of the bit holding part 3 is supported via a bearing 34a on a front frame 10b fixed to the front side of the case 10a of the tool body 10, and the rear end of the rotation guide member 31 is supported via a shaft 41a of the reducer 41 and a bearing 42 on a rear frame 10c fixed to the rear side of the case 10a. Thus, the rotation guide member 31 of the bit holding part 3 is rotatably supported on the tool body 10.

[0040] As a result, the first driving unit 4 rotates the rotary guide member 31 using the bit rotation motor 40. When the rotary guide member 31 rotates, the holding member 30 that holds the driver bit 2 rotates together with the rotary guide member 31 as the connecting member 30b is pressed into the groove portion 31a of the rotary guide member 31.

[0041] The bit holding unit 3 has a guide member 32g provided on the second moving member 32c. The guide member 32g is guided by the connecting member 10d, so that the second moving member 32c can move in the forward and backward directions indicated by arrows A1 and A2 along the axial direction of the driver bit 2, and its rotation following the rotation guide member 31 is restricted.

[0042] Next, the second drive unit 5 will be described with reference to the respective drawings. The second drive unit 5 includes a bit moving motor 50 driven by electricity supplied from the battery 12, and a reducer 51. The bit moving motor 50 is an example of a motor or second motor, and a shaft 50a of the bit moving motor 50 is connected to the reducer 51, and a shaft 51a of the reducer 51 is connected to a pulley 52, which is an example of a transmission member. In the second drive unit 5, the pulley 52 is supported on the tool body 10 via a bearing 53. In the second drive unit 5, the shaft 50a of the bit moving motor 50 is arranged along the extension direction of the handle 11.

[0043] In the second driving unit 5, one end of a linear wire 54, which is an example of a transmission member, is connected to the pulley 52, and the wire 54 is wound around the pulley 52 as the pulley 52 rotates. The other end of the wire 54 is connected to a wire connecting portion 32h provided on the second moving member 32c of the moving member 32.

[0044] As a result, the second drive unit 5 rotates the pulley 52 using the bit moving motor 50 to wind up the wire 54, thereby moving the second moving member 32c forward as indicated by the arrow A1. As the second moving member 32c moves forward, the first moving member 32a is pushed via the bearing 32b, and the first moving member 32a moves forward together with the second moving member 32c along the axial direction of the bit holding unit 3. As the first moving member 32a moves forward, the holding member 30 connected to the first moving member 32a via the connecting member 30b moves forward, and the driver bit 2 held by the holding member 30 moves forward as indicated by the arrow A1.

[0045] The second drive unit 5 is disposed offset to one side from approximately the center in the left-right direction of the fastening tool 1 so that the tangent direction of the portion of the pulley 52 around which the wire 54 is wound is along the extension direction of the rotation guide member 31. In addition, the diameter of the pulley 52 is set so that the wire 54 is not wound around the pulley 52 in an overlapping manner when the pulley 52 winds up the wire 54 to move the driver bit 2 a predetermined distance.

[0046] As a result, the relationship between the amount of rotation of the bit moving motor 50 and the amount of movement of the holding member 30 is one to one throughout the entire movable range of the holding member 30, and by controlling the amount of rotation of the bit moving motor 50, it is possible to control the amount of movement of the holding member 30 along the axial direction of the rotation guide member 31. In other words, by controlling the amount of rotation of the bit moving motor 50, it is possible to control the amount of movement of the driver bit 2 attached to the holding member 30.

[0047] Furthermore, the movement speed of the driver bit 2 can be increased in accordance with the rotation speed of the bit movement motor 50. This reduces the time it takes for the driver bit 2 to press the screw 200 against the object to be fastened.

[0048] Note that the wire 54 is flexible enough to be wound around the pulley 52, and therefore cannot push the second moving member 32c to move the moving member 32 rearward. Therefore, a biasing member 33 is provided that is compressed when the moving member 32 moves forward in the direction indicated by arrow A1, and applies a force to the moving member 32 that pushes the moving member 32 rearward in the direction indicated by arrow A2. This allows the pulley 52 to wind up the wire 54, moving the driver bit 2 forward, and allowing the driver bit 2 to move backward after moving forward.

[0049] 4 is a perspective view showing an example of the screw feed section and nose section of this embodiment, and next, the screw feed section 7 and nose section 8 will be described with reference to each drawing. The screw feed section 7 includes a screw feed motor 70, a pinion gear 71 attached to the shaft of the screw feed motor 70 via a reducer, a rack gear 72 that meshes with the pinion gear 71, and an engagement section 73 that is connected to the rack gear 72 and engages with the connecting screw fed from the screw storage section 6.

[0050] The screw feed unit 7 supports a rack gear 72 so that it can move up and down along the feed direction of the connecting screw. When the screw feed motor 70 rotates forward and backward, the screw feed unit 7 causes an engagement portion 73 that engages with the connecting screw to move back and forth up and down, thereby feeding the connecting screw. Note that the screw feed unit 7 may also be configured to reciprocate the engagement portion 73 using a linear driving unit that combines electromagnetic force, such as a solenoid, with a biasing means.

[0051] The nose portion 8 is provided with an injection passage 80 through which the screw 200 is supplied by the screw feed portion 7 and through which the driver bit 2 passes. The nose portion 8 also has an injection port 81a that communicates with the injection passage 80 and is provided with a contact member 81 that comes into contact with an object to be fastened. The nose portion 8 also has a contact arm 82 that moves in the front-to-rear direction in conjunction with the contact member 81.

[0052] Nose portion 8 supports contact member 81 so that it can move in the front-to-rear direction indicated by arrows A1 and A2, and contact arm 82 moves in the front-to-rear direction in conjunction with contact member 81. In nose portion 8, contact member 81 is urged forward by a urging member (not shown), and contact member 81, which is pressed against an object to be fastened and moves rearward, is then urged forward by the urging member.

[0053] The fastening tool 1 includes a contact switch unit 84 that is activated when pressed by a contact arm 82. The contact switch unit 84 is switched between activated and inactivated when pressed by the contact arm 82 as the contact member 81 is pressed against the object to be fastened and the contact arm 82 moves rearward. In this example, a state in which the contact switch unit 84 is not pressed by the contact arm 82 and is in an inactivated state is referred to as the off state of the contact switch unit 84, and a state in which the contact switch unit 84 is pressed by the contact arm 82 and is activated is referred to as the on state of the contact switch unit 84.

[0054] FIG. 5 is a block diagram showing an example of the fastening tool of this embodiment, and next, the configuration relating to the control and operation of the fastening tool 1 will be described with reference to each drawing.

[0055] The fastening tool 1 includes a trigger 9 that is operated, and a trigger switch unit 90 that is actuated by the operation of the trigger 9. As shown in FIG. 1A and other figures, the trigger 9 is provided on the front side of the handle 11, and is configured to be operable by the fingers of the hand that grips the handle 11. The trigger switch unit 90 is actuated when pressed by the trigger 9.

[0056] The trigger switch unit 90 is switched between activated and inactive when pressed by the trigger 9. In this example, the trigger switch unit 90 is in an inactive state when the trigger 9 is not operated and the trigger 9 does not press the trigger switch unit 90, and is in an off state when the trigger 9 is operated and pressed by the trigger 9, causing the trigger switch unit 90 to be activated.

[0057] The fastening tool 1 is equipped with a control unit 100 that controls the first drive unit 4, the second drive unit 5, and the screw feed unit 7 based on the outputs of a trigger switch unit 90 that is actuated by operating a trigger 9 and a contact switch unit 84 that is actuated by being pressed by a contact member 81. The control unit 100 is composed of a circuit board on which various electronic components are mounted, and is stored in a circuit board storage unit 111 provided on the back side of the screw storage unit 6, between the screw storage unit 6 and the handle 11, as shown in FIG. 1A.

[0058] The control unit 100 controls whether the bit moving motor 50 of the second drive unit 5 and the bit rotation motor 40 of the first drive unit 4 are driven, based on a combination of the on / off states of the contact switch unit 84 and the on / off state of the trigger switch unit 90. The control unit 100 includes a motor state detection unit that detects the state of the bit moving motor 50, and controls the movement speed of the bit holding unit 3 based on the state of the bit moving motor 50 when the screw 200 engaged with the driver bit 2 is fastened into the fastening object. The control unit 100 also includes a first motor state detection unit that detects the state of the bit rotation motor 40, and controls the movement speed of the bit holding unit 3 based on the state of the bit rotation motor 40 when the screw 200 engaged with the driver bit 2 is fastened into the fastening object. The motor state detection unit and the first motor state detection unit may be configured to include detection units that detect the rotation speed (rotational speed) of the bit moving motor 50 and the bit rotation motor 40, respectively, independent of the control unit 100.

[0059] As described above, the fastening tool 1 includes the first drive unit 4 that rotates the driver bit 2 held in the holding member 30 by the bit holding unit 3 by driving the bit rotation motor 40. The fastening tool 1 also includes the second drive unit 5 that moves the driver bit 2 held in the holding member 30 by the bit holding unit 3 in the forward and backward directions along the axial direction by driving the bit movement motor 50.

[0060] In the fastening tool 1, when the bit movement motor 50 rotates in a predetermined direction, the driver bit 2 held by the holding member 30 in the bit holding section 3 moves (advances) in the forward direction indicated by the arrow A1. In addition, when the bit rotation motor 40 rotates in a predetermined direction, the fastening tool 1 rotates the driver bit 2 in the direction for fastening the screw 200.

[0061] The fastening tool 1 advances the driver bit 2 by rotating the bit movement motor 50, thereby engaging the driver bit 2 with the recess 200a of the screw 200, moving the screw 200 forward and pressing it against the object to be fastened.

[0062] Furthermore, the fastening tool 1 rotates the driver bit 2 in a direction for fastening the screw 200 by rotation of the bit rotation motor 40, thereby fastening the screw 200 engaged with the driver bit 2 into the object to be fastened.

[0063] Furthermore, the fastening tool 1 rotates the bit movement motor 50 in conjunction with the rotation of the bit rotation motor 40, thereby moving the driver bit 2 forward in accordance with the fastening of the screw 200.

[0064] Therefore, the control unit 100 controls the amount of movement (advancement) of the driver bit 2 by controlling the amount of rotation of the bit moving motor 50. The control unit 100 controls the amount of movement of the driver bit 2, thereby controlling the stop position of the driver bit 2 along the axial direction.

[0065] Furthermore, the control unit 100 controls the rotation speed of the bit rotation motor 40 and the rotation speed of the bit movement motor 50 to move the driver bit 2 forward in accordance with the fastening of the screw 200 .

[0066] When the driver bit 2 is rotated in the direction of fastening the screw 200 by the rotation of the bit rotation motor 40, the screw 200 engaged with the driver bit 2 is tightened into the object to be fastened, and the screw 200 moves (advances) along the axial direction. The amount of movement (movement speed) of the screw 200 along the axial direction accompanying the rotation of the screw 200 is estimated from the lead angle of the screw 200 and the amount of rotation and rotation speed of the bit rotation motor 40.

[0067] The control unit 100 rotates the bit moving motor 50 at a predetermined rotation speed so that the amount of movement (movement speed) of the driver bit 2 along the axial direction follows the amount of movement (movement speed) of the screw 200.

[0068] The fastening tool 1 moves the screw 200 forward and presses it against the object to be fastened, so that the tip of the screw 200 drills a hole in the surface of the object to be fastened. However, if the object to be fastened is a steel plate, it is more difficult to drill a hole therein than if the object to be fastened is wood, plaster, or the like. When the action of moving the screw 200 forward to drill a hole in an object to be fastened, such as a steel plate, which is difficult to drill holes in, is started, a hole is drilled in the steel plate, and the screw 200 is in a state where it is difficult to advance until the portion of the screw 200 where the threads are formed reaches the steel plate, and therefore the load applied in the axial direction of the driver bit 2 increases. When the load applied in the axial direction of the driver bit 2 increases when the screw 200 is advanced to drill a hole in the object to be fastened, the reaction force of the driver bit 2 pushing the object to be fastened via the screw 200 increases, and the fastening tool 1 may lift off the object to be fastened.

[0069] Therefore, when the screw 200 is moved forward by rotating the bit moving motor 50 to drill a hole in the object to be fastened, such as when the object to be fastened is a steel plate, and the load applied in the axial direction of the driver bit 2 is high, the control unit 100 controls the rotational speed of the bit moving motor 50 to prevent the fastening tool 1 from floating up due to the reaction force of the driver bit 2 pushing the object to be fastened via the screw 200.

[0070] That is, in the fastening tool 1, the tip of the screw 200 is pressed against the object to be fastened by moving (advancing) the driver bit 2 in the axial direction. However, in the case of an object to be fastened that is difficult to drill holes into, such as a steel plate, the load applied to the driver bit 2 in the axial direction becomes high, making it difficult for the screw 200 to advance, and therefore the load when moving (advancing) the driver bit 2 in the axial direction becomes large. For this reason, during the operation of drilling a hole with the screw 200 into an object to be fastened that is difficult to drill holes into, such as a steel plate, the amount of movement (advancement) of the driver bit 2 along the axial direction is reduced compared to when the screw 200 is fastened into an ordinary object to be fastened, such as wood or plaster.

[0071] When the amount of movement (advancement) along the axial direction of the driver bit 2 decreases, the rotational speed of the bit moving motor 50 decreases. Therefore, during the operation of forcing the screw 200 forward to drill a hole in a fastening object that is difficult to drill holes in, such as a steel plate, the amount of decrease in the rotational speed of the bit moving motor 50 becomes greater than when the screw 200 is fastened into a normal fastening object such as wood or plaster.

[0072] On the other hand, when the object to be fastened is one that is difficult to drill holes into, such as a steel plate, the screw 200 will be in an idling state until the tip of the screw 200 drills a hole in the steel plate, so the load applied in the rotational direction of the driver bit 2 will be low and the rotational speed of the bit rotation motor 40 will not decrease compared to when the tip of the screw 200 drills a hole in the object to be fastened and is then tightened into the object to be fastened.

[0073] In this way, when the screw 200 engaged with the driver bit 2 is advanced to drill a hole in the object to be fastened, the rotational speed (amount of rotation) of the bit rotation motor 40 and the rotational speed (amount of rotation) of the bit movement motor 50 change according to the change in the load applied in the axial direction of the driver bit 2 and the change in the load applied in the rotational direction of the driver bit 2.

[0074] The fastening tool 1 determines whether a hole is being drilled in a fastening object that is difficult to drill holes in, such as a steel plate, and controls the bit moving motor 50 in accordance with the fastening object. Therefore, the fastening tool 1 is provided with a load detection unit 112 that detects a change in the load applied in the axial direction of the driver bit 2, or a change in the load applied in the rotational direction of the driver bit 2, or a change in the load applied in the axial direction of the driver bit 2 and a change in the load applied in the rotational direction of the driver bit 2, during the operation of advancing the screw 200 engaged with the driver bit 2 to drill a hole in the fastening object.

[0075] When the driver bit 2 is rotated and moved axially to fasten the screw 200 into the object to be fastened, the load applied to the driver bit 2 in the axial direction and the load applied to the driver bit 2 in the rotational direction both change, and the rotational speed of the bit movement motor 50 and the bit rotation motor 40 decrease.

[0076] However, in the operation of drilling a hole in a fastening object by advancing the screw 200 engaged with the driver bit 2, if a hole is being drilled in a fastening object that is difficult to drill holes in, such as a steel plate, the amount of decrease in the rotational speed of the bit moving motor 50 increases due to an increase in the load applied in the axial direction of the driver bit 2. On the other hand, if a hole is being drilled in a fastening object that is difficult to drill holes in, such as a steel plate, the screw 200 rotates freely, and therefore the amount of decrease in the rotational speed of the bit rotating motor 40 decreases due to a decrease in the load applied in the rotational direction of the driver bit 2.

[0077] Therefore, the load detection unit 112 detects a predetermined change in the load applied in the axial direction of the driver bit 2 and / or the load applied in the rotational direction of the driver bit 2 based on a change in the rotational speed of the bit moving motor 50 and / or the rotational speed of the bit rotating motor 40.

[0078] The load detection unit 112 detects a predetermined load corresponding to the screw 200 being advanced to drill a hole in a fastening object that is difficult to drill holes in, such as a steel plate, based on a predetermined increase in the amount of decrease in the rotational speed of the bit moving motor 50 or a predetermined decrease in the amount of decrease in the rotational speed of the bit rotating motor 40.

[0079] When the control unit 100 determines, based on the predetermined load detected by the load detection unit 112, that the screw 200 is being advanced to drill a hole in a fastening object that is difficult to drill holes in, such as a steel plate, the control unit 100 switches from a first load control in which the bit moving motor 50 is driven with a first output corresponding to the tightening of the screw 200 into a normal fastening object, such as wood or plaster, to a second load control in which the bit moving motor 50 is driven with a second output corresponding to the increase in load when the screw 200 is advanced to drill a hole in a fastening object that is difficult to drill holes in, such as a steel plate. In the second load control, the control unit 100 limits the current flowing to the bit moving motor 50 and reduces the output of the bit moving motor 50, in this case the rotational speed.

[0080] If the rotation of the bit moving motor 50 is maintained at a rotational speed corresponding to the rotational speed of the bit rotation motor 40 in a state in which the movement amount (advancement amount) of the driver bit 2 is reduced due to an increase in the load caused by advancing the screw 200 and pressing it against the object to be fastened, such as a steel plate, and drilling a hole, the actual movement amount (advancement amount) of the driver bit 2 becomes smaller than the axial movement amount (advancement amount) of the screw 200 being fastened by the rotation of the bit rotation motor 40, i.e., the target movement amount (advancement amount) of the driver bit 2 due to the rotation of the bit moving motor 50. As a result, the fastening tool 1 is lifted up by the reaction force of the force of the driver bit 2 pushing the object to be fastened via the screw 200.

[0081] Therefore, in the second load control, the rotational speed of the bit moving motor 50 is reduced to an extent that follows the decrease in the amount of movement (advancement) of the driver bit 2 that occurs as the load of pressing the screw 200 against the object to be fastened to drill a hole increases. As a result, the target amount of movement (advancement) of the driver bit 2 due to the rotation of the bit moving motor 50 and the actual amount of movement (advancement) of the driver bit 2 become approximately equal, suppressing the generation of a reaction force to the force of the driver bit 2 pressing the object to be fastened via the screw 200, and suppressing the fastening tool 1 from floating up.

[0082] The control unit 100 switches from the first load control to the second load control based on, for example, a change in the rotational speed of the bit moving motor 50. Therefore, the control unit 100 sets a high load deceleration threshold value that corresponds to the amount of decrease in the rotational speed of the bit moving motor 50 that accompanies an increase in the load applied in the axial direction of the driver bit 2 as a threshold value for determining whether the screw 200 is being advanced to drill a hole in a fastening object that is difficult to drill, such as a steel plate.

[0083] The high-load deceleration threshold may be set based on the rotation speed of the bit moving motor 50. In this case, when the rotation speed of the bit moving motor 50 falls below the high-load deceleration threshold while the first load control is being executed, the control unit 100 switches to the second load control described above.

[0084] The high-load deceleration threshold may also be set as the difference between a target movement amount of the driver bit 2 calculated from the rotation speed of the bit moving motor 50 and an actual movement amount of the driver bit 2. In this case, the control unit 100 switches to the above-described second load control when the difference between the target movement amount of the driver bit 2 and the actual movement amount of the driver bit 2 becomes equal to or greater than the high-load deceleration threshold while the first load control is being executed. The target movement amount of the driver bit 2 may also be obtained from the axial movement amount of the screw 200 that is fastened by the rotation of the bit rotating motor 40.

[0085] Furthermore, the high-load deceleration threshold may be set as an integrated value of the difference between the target movement amount of the driver bit 2 and the actual movement amount of the driver bit 2. In this case, the control unit 100 acquires the difference between the target movement amount of the driver bit 2 and the actual movement amount of the driver bit 2 at a predetermined sampling interval while executing the first load control, integrates the difference if the difference is equal to or greater than a predetermined threshold, and switches to the above-described second load control if the integrated value of the difference equal to or greater than the predetermined threshold is equal to or greater than the high-load deceleration threshold.

[0086] During the execution of the second load control described above, the control unit 100 executes drilling control to drill holes in a fastening object that is difficult to drill holes in, such as a steel plate.

[0087] In drilling control during execution of the second load control, if the control unit 100 determines that the rotational speed of the bit moving motor 50 does not increase and is below a specified value, the control unit 100 increases the current flowing to the bit moving motor 50 from the current value limited by the second load control. In other words, if the control unit 100 detects that the rotational speed of the bit moving motor 50 does not increase and that the actual movement amount of the driver bit 2 is below a specified value, for example, that the actual movement amount of the driver bit 2 is zero, a specified number of times in succession at a specified sampling interval, the control unit 100 increases the output of the bit moving motor 50, in this case the rotational speed, to gradually increase the movement amount (advancement amount) of the driver bit 2 along the axial direction.

[0088] When the screw 200 drills a hole in a fastening object that is difficult to drill holes in, such as a steel plate, the resistance when the screw 200 moves forward decreases, the load on the bit moving motor 50 decreases, and the rotation speed of the bit moving motor 50 increases. When the control unit 100 determines that the rotation speed of the bit moving motor 50 is equal to or greater than a specified value during drilling control while the second load control is being executed, it switches from the second load control to the first load control and releases the restriction on the current flowing to the bit moving motor 50.

[0089] The fastening tool 1 includes a setting unit 110 that sets the amount of rotation of the bit moving motor 50, which determines the amount of advancement of the driver bit 2. Fig. 6 is a perspective view showing an example of the setting unit, and next, the setting unit 110 will be described with reference to each drawing.

[0090] The setting unit 110 is an example of a setting means, and is configured to allow any setting value to be selected from a plurality of setting values, or to allow any setting value to be selected in a stepless manner.

[0091] In this example, the setting unit 110 is configured such that a setting value is selected using an operation unit 110a that is made up of buttons. Alternatively, the operation unit 110a may be configured such that a setting value is selected using a rotary dial. Alternatively, the setting unit 110 may be configured to display the selected setting value by, for example, indicating the current value with a label or engraving, or by indicating the current value on a display unit 110b such as an LED, so that the operator can easily grasp the current setting value. The information displayed on the display unit 110b includes the setting value of the screw depth that is determined by the advancement amount of the driver bit 2, the power ON / OFF status, the selected operation mode from various selectable operation modes, the presence or absence of a screw, the remaining amount of screws, the presence or absence of an abnormality, etc.

[0092] The setting sections 110 are provided on both the left and right sides of the surface facing the handle 11 in the board storage section 111 provided on the rear side of the screw storage section 6.

[0093] This makes it possible to visually recognize the setting portion 110 from both the left and right sides of the handle 11 when the fastening tool 1 is viewed from the rear.

[0094] <Example of operation of the fastening tool according to this embodiment> Figures 7A and 7B are flowcharts showing an example of the operation of the fastening tool of this embodiment, Figures 8A and 8B are graphs showing the relationship between the rotational speeds of the bit rotation motor and the bit movement motor, and Figures 9A, 9B, and 9C are cross-sectional views showing the fastening state of a screw.Next, with reference to each figure, an example of the fastening operation of the fastening tool of this embodiment will be described.

[0095] In the fastening tool 1, in the standby state, the tip of the driver bit 2 is located at a standby position P1 behind the injection passage 80 as shown in FIG. 1A, and the screw 200 can be supplied to the injection passage 80.

[0096] 7A, the control unit 100 sets the amount of rotation of the bit moving motor 50, which determines the amount of advancement of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the fastening target 202, the contact switch unit 84 is pressed by the contact arm 82, the contact switch unit 84 is turned on in step SA2, the trigger 9 is operated, and the trigger switch unit 90 is turned on in step SA3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SA4 and drives the bit moving motor 50 of the second drive unit 5 in step SA5, thereby executing the first load control.

[0097] When the bit moving motor 50 is driven to rotate in one direction, which is the forward direction, the pulley 52 rotates in the forward direction, causing the wire 54 to be wound around the pulley 52. ​​As the wire 54 is wound around the pulley 52, the second moving member 32c connected to the wire 54 is guided by the rotation guide member 31 and moves forward in the axial direction. When the second moving member 32c moves forward, the first moving member 32a is pushed by the second moving member 32c via the bearing 32b, and moves forward in the axial direction together with the second moving member 32c while compressing the biasing member 33.

[0098] When the first moving member 32a moves forward, the holding member 30 connected to the first moving member 32a by the connecting member 30b moves forward along the axial direction of the driver bit 2, with the connecting member 30b being guided by the groove portion 31a of the rotating guide member 31.

[0099] As a result, the driver bit 2 held by the holding member 30 moves forward as indicated by the arrow A1, engages with the screw 200 supplied to the injection port 81a of the nose portion 8, and moves the screw 200 forward, pressing it against the object 202 to be fastened.

[0100] Furthermore, when the bit rotation motor 40 is driven to rotate in one direction, that is, the forward direction, the rotation guide member 31 rotates in the forward direction. When the rotation guide member 31 rotates in the forward direction, the connecting member 30b connected to the holding member 30 is pressed against the groove portion 31a of the rotation guide member 31, causing the holding member 30 to rotate together with the rotation guide member 31.

[0101] As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and tightens it into the object to be fastened 202. The control unit 100 moves the driver bit 2 forward with the second drive unit 5 based on the load on the bit rotation motor 40, the rotation speed of the bit rotation motor 40, the load on the bit movement motor 50, the rotation speed of the bit movement motor 50, etc., in conjunction with the operation of rotating the driver bit 2 with the first drive unit 4 to tighten the screw into the object to be fastened 202, thereby causing the driver bit 2 to follow the screw 200 being tightened into the object to be fastened 202.

[0102] Figure 8A shows the relationship between the rotational speeds of the bit rotation motor 40 and the bit movement motor 50 when a screw 200 is fastened into a normal object 202 to be fastened, such as wood or plaster, and Figure 8B shows the relationship between the rotational speeds of the bit rotation motor 40 and the bit movement motor 50 when an object 202 to be fastened, such as plaster, is placed on top of a steel plate 203 as a base and the screw 200 is fastened into the steel plate 203.

[0103] When the operation of rotating the driver bit 2 to fasten the screw 200 into the object to be fastened 202 begins, a load is generated on the driver bit 2 via the screw 200 in step SA6. When a load is generated on the driver bit 2, the rotation speed V1 of the bit rotation motor 40 and the rotation speed V2 of the bit movement motor 50 both decrease. However, the load applied to the driver bit 2 via the screw 200 differs between when the screw 200 is fastened into a normal object to be fastened 202 such as wood or plaster and when the object to be fastened 202 such as plaster is placed on a base of a steel plate 203 and the screw 200 is fastened into the steel plate 203.

[0104] In particular, in the case of steel plate 203 or the like that is difficult to drill holes into, when the tip of screw 200 reaches steel plate 203, as shown in Fig. 9A, the load when pressing screw 200 against steel plate 203 is larger than that when screwing into wood or plaster, and the load when moving driver bit 2 axially (advancing) is also larger. As a result, the amount of decrease in rotation speed V2 of bit moving motor 50 is larger when screw 200 is fastened into steel plate 203 shown in Fig. 8B compared to when screw 200 is fastened into a normal fastening target 202 such as wood or plaster shown in Fig. 8A.

[0105] Therefore, in step SA7, the control unit 100 compares the rotational speed V2 of the bit moving motor 50 with the high-load deceleration threshold S to determine whether the amount of decrease in the rotational speed of the bit moving motor 50 is within the range of normal deceleration.

[0106] After the load generation timing T1, when the control unit 100 determines that the rotational speed V2 of the bit moving motor 50 does not fall below the high-load deceleration threshold S as shown in FIG. 8A and that the amount of decrease in the rotational speed of the bit moving motor 50 is within the range of normal deceleration, it determines that the screw 200 is being fastened into a normal fastening object 202 such as wood or plaster, and continues the first load control.

[0107] When the control unit 100 determines in step SA8 that the amount of rotation of the bit moving motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position, at timing T2 when the driver bit 2 has moved the specified amount shown in Figure 8A, it stops driving the bit rotation motor 40 in step SA9, stops the rotation of the bit moving motor 50 in the forward direction in step SA10, and then reverses the rotation of the bit moving motor 50 in step SA11.

[0108] When the bit moving motor 50 rotates in the other direction, that is, the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52. ​​When the wire 54 is pulled out from the pulley 52, the second moving member 32c moves forward, causing the compressed biasing member 33 to expand and push the second moving member 32c rearward.

[0109] The second moving member 32c is pushed rearward by the biasing member 33, and moves rearward along the axial direction while being guided by the rotation guide member 31. When the second moving member 32c moves rearward, the first moving member 32a is pulled by the second moving member 32c via the bearing 32b, and moves rearward along the axial direction together with the second moving member 32c.

[0110] When the first moving member 32a moves rearward, the holding member 30 connected to the first moving member 32a by the connecting member 30b moves rearward along the axial direction of the driver bit 2, with the connecting member 30b being guided by the groove portion 31a of the rotating guide member 31.

[0111] In step SA12, the control unit 100 reverses the bit moving motor 50 to the initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and the moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SA13.

[0112] When the trigger switch unit 90 is turned off, the control unit 100 rotates the screw feed motor 70 in one direction to lower the engaging unit 73. When the engaging unit 73 has lowered to a position where it can engage with the next screw 200, the control unit 100 reverses the rotation of the screw feed motor 70 to raise the engaging unit 73 and supply the next screw 200 to the injection passage 80.

[0113] When the control unit 100 compares the rotational speed V2 of the bit moving motor 50 with the high-load deceleration threshold value in step SA7 and determines that the rotational speed V2 of the bit moving motor 50 falls below the high-load deceleration threshold value S and that the amount of reduction in the rotational speed of the bit moving motor 50 is greater than or equal to the normal deceleration range, as shown in FIG. 8B , it determines that the screw 200 is being pressed against the steel plate 203, and switches from the first load control to the second load control in step SA14. In the second load control, the control unit 100 limits the current flowing to the bit moving motor 50 and reduces the output of the bit moving motor 50, in this case the rotational speed. In this way, the timing T2 at which the current limitation begins is when the rotational speed V2 of the bit moving motor 50 falls below the high-load deceleration threshold value S.

[0114] The control unit 100 executes drilling control to drill a hole in the steel plate 203 while executing the second load control in which the rotation of the bit rotating motor 40 is continued while limiting the rotation speed of the bit moving motor 50.

[0115] In the drilling section E1 where drilling control is performed while the second load control is being executed, the control unit 100 detects the rotational speed of the bit moving motor 50 at a predetermined sampling interval, and at timing T3 for determining whether or not the current limit shown in Figure 8B should be relaxed, determines whether the rotational speed of the bit moving motor 50 is greater than or equal to a specified value for canceling the second load control.

[0116] If the control unit 100 determines in step SA15 that the rotational speed of the bit moving motor 50 has not reached the specified value for canceling the second load control, then in step SA16 it increases the current flowing to the bit moving motor 50 from the current value limited by the second load control. By increasing the current flowing to the bit moving motor 50, the output of the bit moving motor 50, in this case the rotational speed, is increased, and the amount of movement (advancement) of the driver bit 2 along the axial direction is gradually increased.

[0117] This gradually increases the force that presses the screw 200 against the object to be fastened via the driver bit 2, suppressing an increase in the reaction force of the force that the driver bit 2 presses the object to be fastened via the screw 200, and makes it easier to drill a hole in the steel plate 203, as shown in Figure 9B.

[0118] When the control unit 100 determines in step SA15 that the rotational speed of the bit moving motor 50 is equal to or greater than the specified value for releasing the second load control, it switches from the second load control to the first load control in step SA17, and releases the restriction on the current flowing to the bit moving motor 50 at timing T4 for releasing the current restriction shown in Figure 8B.

[0119] 9C , when the screw 200 drills a hole in the steel plate 203, the screw 200 becomes able to move (advance) in the axial direction, and the load when the driver bit 2 moves (advance) in the axial direction decreases. As a result, the amount of movement of the driver bit 2 along the axial direction can follow the amount of movement of the screw 200 along the axial direction when the screw 200 rotates and is fastened into the steel plate 203, and the rotation speed of the bit-moving motor 50 increases. Therefore, by releasing the restriction on the current flowing to the bit-moving motor 50, in the screw fastening section E2, the driver bit 2 can follow the screw 200 being fastened into the fastening object 202 and the steel plate 203, and the screw 200 can be fastened into the fastening object 202 and the steel plate 203.

[0120] In addition, during the drilling section E1 where drilling control is performed while the second load control is being executed, the control unit 100 may detect the rotational speed of the bit rotation motor 40 at a predetermined sampling interval and determine whether the decrease in the rotational speed of the bit rotation motor 40 is equal to or greater than a specified value for canceling the second load control of the bit moving motor 50 at timing T3, shown in FIG. 8B , for determining whether or not to relax the current limit. During the drilling section E1 where drilling control is performed while the second load control is being executed, as shown by the dashed-dotted line in FIG. 8B , after the decrease in the rotational speed of the bit rotation motor 40 decreases due to the screw 200 spinning freely, the decrease in the rotational speed of the bit rotation motor 40 may increase again due to an increase in load, such as when the steel plate 203 begins to drill. Therefore, when the control unit 100 determines that the decrease in the rotational speed of the bit rotation motor 40 has increased and is equal to or greater than the specified value for canceling the second load control of the bit moving motor 50, it increases the current flowing to the bit moving motor 50 from the current value limited by the second load control.

[0121] The operation of fastening the screw 200 into the steel plate 203 is similar to that of a normal fastening object, and when the control unit 100 determines in step SA8 that the amount of rotation of the bit moving motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position, at timing T5 when the driver bit 2 has moved the specified amount as shown in Figure 8B, it stops driving the bit rotation motor 40 in step SA9, stops the rotation of the bit moving motor 50 in the forward direction in step SA10, and then reverses the rotation of the bit moving motor 50 in step SA11.

[0122] When the holding member 30 and the moving member 32 move rearward to a position where the tip of the driver bit 2 returns to the standby position P1 in step SA12, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SA13.

[0123] 10A and 10B are flowcharts illustrating another example of the operation of the fastening tool of this embodiment, and FIGS. 11A, 11B, and 11C are graphs illustrating the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. Next, another example of the fastening operation of the fastening tool of this embodiment will be described with reference to these figures. In this other example of the fastening operation, in the fastening tool 1 that switches between the first load control and the second load control described above, the setting unit 110 can switch between a first control mode in which the second load control is performed regardless of the magnitude of the load applied in the axial direction of the driver bit 2, and a second control mode in which the second load control is performed depending on the magnitude of the load applied in the axial direction of the driver bit 2. Therefore, the setting unit 110 is an example of a mode switching unit that can switch the control mode between the first control mode and the second control mode. The second load control is also referred to as a steel plate mode.

[0124] In the fastening tool 1, the setting unit 110 selects whether or not to execute the first control mode and the second control mode in step SB1 of FIG. 10A.

[0125] In step SB2, the control unit 100 sets the amount of rotation of the bit moving motor 50, which determines the amount of advancement of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact switch unit 84 is turned on in step SB3 and the trigger switch unit 90 is turned on in step SB4, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SB5 and drives the bit moving motor 50 of the second drive unit 5 in step SB6.

[0126] When the bit moving motor 50 is driven to rotate in one direction, that is, the forward direction, the driver bit 2 held by the holding member 30 of the bit holding portion 3 moves forward as indicated by the arrow A1, engages with the screw 200 supplied to the injection port 81a of the nose portion 8, moves the screw 200 forward, and presses it against the object to be fastened.

[0127] Furthermore, when the bit rotation motor 40 is driven to rotate in one direction, that is, the forward direction, the driver bit 2 held by the holding member 30 of the bit holding unit 3 rotates the screw 200 in the forward direction (clockwise) and drives it into the object to be fastened. The control unit 100, in conjunction with the operation of the first drive unit 4 to rotate the driver bit 2 and drive the screw into the object to be fastened, moves the driver bit 2 forward with the second drive unit 5 based on the load on the bit rotation motor 40, the rotation speed of the bit rotation motor 40, the load on the bit movement motor 50, the rotation speed of the bit movement motor 50, etc., thereby causing the driver bit 2 to follow the screw 200 being driven into the object to be fastened.

[0128] When the driver bit 2 is rotated to start the operation of fastening the screw 200 into the object 202 to be fastened, a load is generated on the driver bit 2 via the screw 200. When the control unit 100 detects the load caused by fastening the screw 200 in step SB7, it determines in step SB8 whether or not execution of the first control mode has been selected.

[0129] 11A, when the control unit 100 determines that execution of the first control mode has been selected, it detects the load caused by fastening the screw 200 in step SB7 described above and determines that the movement speed of the bit holding unit 3 has decreased when fastening the screw 200 engaged with the driver bit 2 into the fastening object 202, and then switches from the first load control to the second load control in step SB9 without detecting or determining the magnitude of the load applied in the axial direction of the driver bit 2. In the second load control, the control unit 100 limits the current flowing to the bit moving motor 50 and reduces the output of the bit moving motor 50, in this case the rotational speed.

[0130] The control unit 100 executes drilling control to drill a hole in the steel plate 203 while executing the second load control in which the rotation of the bit rotating motor 40 is continued while limiting the rotation speed of the bit moving motor 50.

[0131] In the drilling section E1 where drilling control is performed while the second load control is being executed, the control unit 100 detects the rotational speed of the bit moving motor 50 at a predetermined sampling interval, and at the timing T2 for determining whether or not the current limit should be relaxed, determines whether the rotational speed of the bit moving motor 50 is greater than or equal to a specified value for canceling the second load control.

[0132] If the control unit 100 determines in step SB10 that the rotational speed of the bit moving motor 50 has not reached the specified value for canceling the second load control, then in step SB11 it increases the current flowing to the bit moving motor 50 from the current value limited by the second load control. By increasing the current flowing to the bit moving motor 50, the output of the bit moving motor 50, in this case the rotational speed, is increased, and the movement amount (advance amount) of the driver bit 2 along the axial direction is gradually increased.

[0133] This gradually increases the force that presses the screw 200 against the object to be fastened via the driver bit 2, making it easier to drill a hole in the steel plate 203 while suppressing an increase in the reaction force of the force that the driver bit 2 presses against the object to be fastened via the screw 200.

[0134] When the control unit 100 determines in step SB10 that the rotational speed of the bit moving motor 50 is equal to or greater than the specified value for releasing the second load control, it switches from the second load control to the first load control in step SB12, and releases the restriction on the current flowing to the bit moving motor 50 at timing T3 for releasing the current restriction.

[0135] That is, when the screw 200 drills a hole in the steel plate 203, the screw 200 becomes able to move (advance) in the axial direction, and the load when the driver bit 2 moves (advance) in the axial direction decreases. As a result, the amount of movement of the driver bit 2 along the axial direction can follow the amount of movement of the screw 200 along the axial direction when the screw 200 rotates and is fastened into the steel plate 203, and the rotation speed of the bit moving motor 50 increases. Therefore, by releasing the restriction on the current flowing to the bit moving motor 50, in the screw fastening section E2, the driver bit 2 can follow the screw 200 being fastened into the fastening object 202 and the steel plate 203, and the screw 200 can be fastened into the fastening object 202 and the steel plate 203.

[0136] When the control unit 100 determines in step SB13 that the amount of rotation of the bit moving motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position, at timing T4 when the driver bit 2 has moved the specified amount, it stops driving the bit rotation motor 40 in step SB14, stops the rotation of the bit moving motor 50 in the forward direction in step SB15, and then reverses the rotation of the bit moving motor 50 in step SB16.

[0137] In step SB17, when the holding member 30 and the moving member 32 move rearward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SB18.

[0138] If the control unit 100 determines in step SB8 that execution of the first control mode has not been selected, then in step SB19, the control unit 100 compares the rotational speed V2 of the bit moving motor 50 with the high-load deceleration threshold S to determine whether the amount of reduction in the rotational speed of the bit moving motor 50 is within the range of normal deceleration. If the control unit 100 determines that, after timing T1 of detecting a load caused by fastening the screw 200, the rotational speed V2 of the bit moving motor 50 does not fall below the high-load deceleration threshold S, as shown in FIG. 11B , the movement speed of the bit holder 3 exceeds a predetermined speed when fastening the screw 200 engaged with the driver bit 2 into the workpiece 202, and the amount of reduction in the rotational speed of the bit moving motor 50 is within the range of normal deceleration, then the control unit 100 determines that the screw 200 is being fastened into a normal workpiece 202, such as wood or plaster, and continues the first load control described above.

[0139] If the control unit 100 determines in step SB8 that execution of the first control mode has not been selected, and determines in step SB19 that the rotational speed V2 of the bit moving motor 50 has fallen below the high-load deceleration threshold S, as shown in Fig. 11C, the movement speed of the bit holder 3 has fallen below a predetermined speed when fastening the screw 200 engaged with the driver bit 2 into the workpiece 202, and the amount of reduction in the rotational speed of the bit moving motor 50 is greater than or equal to the range of normal deceleration, then in step SB9 the control unit 100 switches from the first load control to the second load control and executes the second load control described above. In the second load control, the control unit 100 limits the current flowing to the bit moving motor 50 and reduces the output of the bit moving motor 50, in this case the rotational speed.

[0140] 12A and 12B are flowcharts showing another example of the operation of the fastening tool of this embodiment, and Fig. 13 is a graph showing the relationship between the rotational speeds of the bit rotating motor and the bit moving motor. Next, with reference to these figures, yet another example of the fastening operation of the fastening tool of this embodiment will be described. In yet another example of the fastening operation, in the fastening tool 1 that switches between the first load control and the second load control described above, advance / advance control is executed at a predetermined timing on the bit rotating motor 40 that rotates the driver bit 2, thereby increasing the rotational speed.

[0141] Specifically, advance angle control is achieved by using a motor equipped with a sensor that detects the change in rotor magnetic force direction at the normal 30-degree advance angle position, and delaying the change in energization from the point at which the sensor signal is detected, which is one commutation earlier than the normal energization state.

[0142] In step SC1, the control unit 100 sets the amount of rotation of the bit moving motor 50, which determines the amount of advancement of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact switch unit 84 is turned on in step SC2 and the trigger switch unit 90 is turned on in step SC3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SC4 and drives the bit moving motor 50 of the second drive unit 5 in step SC5.

[0143] The control unit 100 does not execute lead angle control until the rotation speed increases to a specified value after starting to drive the bit rotation motor 40. This is because the torque becomes weak when lead angle control is executed, and therefore it takes time for the rotation speed to increase if lead angle control is executed immediately after starting to drive.

[0144] When the bit moving motor 50 is driven to rotate in one direction, that is, the forward direction, the driver bit 2 held by the holding member 30 of the bit holding portion 3 moves forward as indicated by the arrow A1, engages with the screw 200 supplied to the injection port 81a of the nose portion 8, moves the screw 200 forward, and presses it against the object to be fastened.

[0145] Furthermore, when the bit rotation motor 40 is driven to rotate in one direction, that is, the forward direction, the driver bit 2 held by the holding member 30 of the bit holding unit 3 rotates the screw 200 in the forward direction (clockwise) and drives it into the object to be fastened. The control unit 100, in conjunction with the operation of the first drive unit 4 to rotate the driver bit 2 and drive the screw into the object to be fastened, moves the driver bit 2 forward with the second drive unit 5 based on the load on the bit rotation motor 40, the rotation speed of the bit rotation motor 40, the load on the bit movement motor 50, the rotation speed of the bit movement motor 50, etc., thereby causing the driver bit 2 to follow the screw 200 being driven into the object to be fastened.

[0146] When the operation of rotating the driver bit 2 to fasten the screw 200 into the object 202 is started, in step SC6 a load is applied to the driver bit 2 via the screw 200. When a load is applied to the driver bit 2, in step SC7 the control unit 100 compares the rotation speed V2 of the bit moving motor 50 with the high-load deceleration threshold S to determine whether the amount of reduction in the rotation speed of the bit moving motor 50 is within the range of normal deceleration.

[0147] When the control unit 100 compares the rotation speed V2 of the bit moving motor 50 with the high-load deceleration threshold value in step SC7 and determines that the rotation speed V2 of the bit moving motor 50 is below the high-load deceleration threshold value S and that the amount of reduction in the rotation speed of the bit moving motor 50 is greater than or equal to the normal deceleration range, as shown in Fig. 13, it determines that the screw 200 is being pressed against the steel plate 203, and switches from the first load control to the second load control in step SC8. In the second load control, the control unit 100 limits the current flowing to the bit moving motor 50 and reduces the output of the bit moving motor 50, in this case the rotation speed.

[0148] When the control unit 100 switches from the first load control to the second load control, it executes lead / advance control in step SC9. In the case of a fastening object that is difficult to drill holes into, such as a steel plate, the screw 200 is in an idling state until the tip of the screw 200 drills a hole in the steel plate, and the load applied in the rotation direction of the driver bit 2 is low. If lead / advance control is executed on the bit rotation motor 40 when the load applied to the bit rotation motor 40 is light, the rotation speed of the bit rotation motor 40 will further increase.

[0149] As a result, when the tip of the screw 200 reaches the steel plate, the rotation speed of the bit rotation motor 40 is increased, thereby facilitating the drilling of a hole in the steel plate by the idling of the screw 200.

[0150] The control unit 100 executes drilling control to drill a hole in the steel plate 203 while executing the second load control in which the rotation of the bit rotating motor 40 is continued while limiting the rotation speed of the bit moving motor 50.

[0151] In the drilling section E1 where drilling control is performed while the second load control is being executed, the control unit 100 detects the rotational speed of the bit moving motor 50 at a predetermined sampling interval, and at timing T3 for determining whether or not the current limit shown in Figure 13 should be relaxed, determines whether the rotational speed of the bit moving motor 50 is greater than or equal to a specified value for canceling the second load control.

[0152] If the control unit 100 determines in step SC10 that the rotational speed of the bit moving motor 50 has not reached the specified value for canceling the second load control, then in step SC11 it increases the current flowing to the bit moving motor 50 from the current value limited by the second load control. By increasing the current flowing to the bit moving motor 50, the output of the bit moving motor 50, in this case the rotational speed, is increased, and the amount of movement (advancement) of the driver bit 2 along the axial direction is gradually increased.

[0153] This gradually increases the force that presses the screw 200 against the object to be fastened via the driver bit 2, making it easier to drill a hole in the steel plate 203 while suppressing an increase in the reaction force of the force that the driver bit 2 presses against the object to be fastened via the screw 200.

[0154] If the control unit 100 determines in step SC10 that the rotation speed of the bit moving motor 50 is equal to or greater than the specified value for canceling the second load control, it switches from the second load control to the first load control in step SC12, and cancels the limit on the current flowing to the bit moving motor 50 at timing T4 for canceling the current limit shown in Fig. 11. After switching from the second load control to the first load control, the control unit 100 stops the advance angle control in step SC13.

[0155] That is, when the screw 200 drills a hole in the steel plate 203, the screw 200 becomes able to move (advance) in the axial direction, and the load when the driver bit 2 moves (advance) in the axial direction decreases. As a result, the amount of movement of the driver bit 2 along the axial direction can follow the amount of movement of the screw 200 along the axial direction when the screw 200 rotates and is fastened into the steel plate 203, and the rotation speed of the bit moving motor 50 increases. Therefore, by releasing the restriction on the current flowing to the bit moving motor 50, in the screw fastening section E2, the driver bit 2 can follow the screw 200 being fastened into the fastening object 202 and the steel plate 203, and the screw 200 can be fastened into the fastening object 202 and the steel plate 203.

[0156] When the control unit 100 determines in step SC14 that the amount of rotation of the bit moving motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position, at timing T5 when the driver bit 2 has moved the specified amount as shown in Figure 13, it stops driving the bit rotation motor 40 in step SC15, stops the rotation of the bit moving motor 50 in the forward direction in step SC16, and then reverses the rotation of the bit moving motor 50 in step SC17.

[0157] When the holding member 30 and the moving member 32 move rearward to a position where the tip of the driver bit 2 returns to the standby position P1 in step SC18, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SC19.

[0158] If the control unit 100 determines that, as the rotational speed V2 of the bit moving motor 50 decreases after the load generation timing T1, the rotational speed V2 of the bit moving motor 50 does not fall below the high-load deceleration threshold S and the amount of decrease in the rotational speed of the bit moving motor 50 is within the range of normal deceleration, it determines that the screw 200 is being fastened into a normal fastening object 202 such as wood or plaster, and continues the first load control. [Explanation of symbols]

[0159] DESCRIPTION OF SYMBOLS 1 Fastening tool, 10 Tool body, 11 Handle, 2 Driver bit, 3 Bit holding portion, 30 Holding member, 31 Rotation guide member, 32 Moving member, 33 Pressing member, 4 First drive portion, 40 Bit rotation motor (first motor), 5 Second drive portion, 50 Bit movement motor (motor, second motor), 52 Pulley, 54 Wire, 6 Screw storage portion, 7 Screw feed portion, 8 Nose portion, 81 Contact member, 84 Contact switch portion, 9 Trigger, 90 Trigger switch portion, 100 Control portion (motor state detection portion, first motor state detection portion), 110 Setting portion (mode switching portion), 112 Load detection portion

Claims

1. a bit holding portion that holds a driver bit that can be engaged with a screw and is rotatable in a circumferential direction of the driver bit and movable in an axial direction; a first motor that rotates the bit holding portion; a second motor that moves the bit holding portion in the axial direction; a control unit that controls the rotation speed of the bit holding unit via the first motor and controls the output of the second motor to control the movement speed of the bit holding unit; a first motor state detection unit that detects a state of the first motor; Equipped with The control unit controls the moving speed of the bit holding unit based on the state of the first motor when the screw engaged with the driver bit is fastened into a fastening object. Fastening tools.

2. The state of the first motor is the rotation speed of the first motor. The fastening tool according to claim 1 .

3. The control unit controls the moving speed of the bit holding unit based on the amount of reduction in the rotation speed of the first motor when fastening the screw engaged with the driver bit into a fastening object. The fastening tool according to claim 2 .

4. The control unit reduces the output of the second motor when the amount of reduction in the rotational speed of the first motor decreases when the screw engaged with the driver bit is fastened into a fastening object. The fastening tool according to claim 3 .

5. The control unit increases the output of the second motor when the amount of decrease in the rotational speed of the first motor decreases when the screw engaged with the driver bit is fastened into a fastening object, and then the amount of decrease increases again. The fastening tool according to claim 4.

6. The control unit executes lead / advance angle control for the first motor. The fastening tool according to claim 5.

7. The control unit executes advance / advance angle control on the first motor after reducing the moving speed of the bit holding unit. The fastening tool according to claim 6.

Images