Agreement tools

Abstract

To provide a fastening tool which can suppress reaction force of a force pushing a fastening object by a driver bit moving in an axial direction via a screw in the case that a load is high when drilling a hole in the fastening object with the screw.SOLUTION: A fastening tool 1 comprises: a bit rotating motor 40 which rotates a driver bit; a bit moving motor 50 which moves the driver bit along an axial direction; a load detection part 112 which detects a load such that a screw engaged with the driver bit contacts a fastening object and drills a hole; and a control part 100 which lowers output of the bit moving motor 50 from first output to second output when the load such that the screw engaged with the driver bit contacts the fastening object and drills the hole by an operation for rotating the bit rotating motor 50 with the first output and moving the driver bit held by a bit holding part 3 in an axial direction is detected by the load detection part 112.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a fastening tool that engages a driver bit with a screw, presses the screw with the driver bit against a fastening object, and rotates the driver bit to screw it in.

Background Art

[0002] There is known a tool called a portable driving machine that uses the air pressure of compressed air supplied from an air compressor or the combustion pressure of gas to sequentially drive out the connecting fasteners loaded in a magazine from the tip of a driver guide.

[0003] Conventionally, there has been proposed a pneumatic screw driving machine that rotates a bit with an air motor and moves it in the direction of driving in a screw with air pressure (see, for example, Patent Document 1).

[0004] Also, there has been proposed a screw driving machine that compresses a spring with the driving force of a motor that rotates a driver bit and moves the driver bit in the axial direction by the biasing force of the spring to drive in a screw (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] One common task using a screw driving machine is to drive screws into a component consisting of gypsum board placed on a steel plate base. However, in a configuration where the driver bit is moved axially by spring force to drive the screw, it is difficult to control the movement speed of the bit holder. For example, even when the screw has not yet penetrated the steel plate due to the spring force, the driver bit continues to advance due to the spring force, causing the fastening tool to lift due to the reaction force of the driver bit pushing the object being fastened through the screw.

[0007] The present invention aims to solve these problems and provides a fastening tool that allows control over the movement speed of the bit holder. [Means for solving the problem]

[0008] To solve the above-mentioned problems, the present invention provides a bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, a motor that moves the bit holder in the axial direction, a control unit that controls the output of the motor to control the movement speed of the bit holder, and a motor state detection unit that detects the rotation speed of the motor. , a contact member that is pressed against the object to be fastened and The control unit is equipped with, With the contact member pressed against the object to be fastened, the motor moves the bit holder axially, causing the driver bit to advance axially. Screw engaged with the driver bit in To the items subject to the contract Make a hole edge This is due to changes in the load applied to the driver bit in the axial direction. Motor rotation speed Change Based on this, the movement speed of the bit holder is controlled, and when fastening the screw engaged with the driver bit to the object to be fastened... , which can be calculated from the motor's rotation speed. The movement speed of the bit holding part The movement of the bit holder corresponds to the decrease in motor rotation speed as the load on the driver bit in the axial direction increases. speed below When that happened, As the load increases when pressing the screw against the object to be fastened and drilling a hole, the amount of movement of the driver bit decreases, so as to follow this, This is a fastening tool that reduces the output of a motor. Furthermore, the present invention includes a bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, a motor that moves the bit holder in the axial direction, a control unit that controls the output of the motor to control the movement speed of the bit holder, a motor state detection unit that detects the rotation speed of the motor, and a control mode This implements a control mechanism that reduces the motor output regardless of the magnitude of the load applied to the driver bit in the axial direction. First control mode and The system performs control to reduce the motor output according to the magnitude of the load applied to the driver bit in the axial direction.A mode switching unit that can switch between the second control mode and the second control mode. , a contact member that is pressed against the object to be fastened and The control unit is equipped with, With the contact member pressed against the object to be fastened, the motor moves the bit holder axially, causing the driver bit to advance axially. Screw engaged with the driver bit in To the items subject to the contract Make a hole edge This is due to changes in the load applied to the driver bit in the axial direction. Motor rotation speed Change Based on this, the movement speed of the bit holder is controlled, and when the control mode is the first control mode, when fastening the screw engaged with the driver bit to the object to be fastened... , by motor If it is determined that the movement speed of the bit holder has decreased, As the load increases when pressing the screw against the object to be fastened and drilling a hole, the amount of movement of the driver bit decreases, so as to follow this, When the motor output is reduced and the control mode is in the second control mode, when fastening a screw engaged with the driver bit to the object to be fastened... , which can be calculated from the motor's rotation speed. The movement speed of the bit holding part The movement of the bit holder corresponds to the decrease in motor rotation speed as the load on the driver bit in the axial direction increases. speed below If we determine that, As the load increases when pressing the screw against the object to be fastened and drilling a hole, the amount of movement of the driver bit decreases, so as to follow this, This is a fastening tool that reduces the output of a motor. Furthermore, the present invention includes a bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, a motor that moves the bit holder in the axial direction, a control unit that controls the output of the motor to control the movement speed of the bit holder, and a motor state detection unit that detects the rotational speed of the motor. , a contact member that is pressed against the object to be fastened and Equipped with, With the contact member pressed against the object to be fastened, the motor moves the bit holder axially, causing the driver bit to advance axially. Screw engaged with the driver bit in To the items subject to the contract Make a hole edge This is due to changes in the load applied to the driver bit in the axial direction. Motor rotation speed Change Based on this, the movement speed of the bit holder is controlled, and when fastening the screw engaged with the driver bit to the object to be fastened... , which can be calculated from the motor's rotation speed. The difference between the actual movement of the bit holder and the target movement is A threshold corresponding to the amount of decrease in motor rotational speed due to an increase in the load applied to the driver bit in the axial direction. When it exceeds the value, As the load increases when pressing the screw against the object to be fastened and drilling a hole, the amount of movement of the driver bit decreases, so as to follow this, This is a fastening tool that reduces the output of a motor. Furthermore, the present invention includes a bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, a motor that moves the bit holder in the axial direction, a control unit that controls the output of the motor to control the movement speed of the bit holder, and a motor state detection unit that detects the rotational speed of the motor. , a contact member that is pressed against the object to be fastened and Equipped with, With the contact member pressed against the object to be fastened, the motor moves the bit holder axially, causing the driver bit to advance axially.A screw engaged with a driver bit in To the object to be fastened Make a hole During This is due to changes in the load applied to the driver bit in the axial direction. The rotational speed of the motor Change Based on this, the moving speed of the bit holding part is controlled, and when fastening the screw engaged with the driver bit to the object to be fastened , which can be calculated from the motor's rotation speed. When the integrated value of the difference between the actual moving amount and the target moving amount of the bit holding part A threshold corresponding to the amount of decrease in motor rotational speed due to an increase in the load applied to the driver bit in the axial direction. Becomes equal to or more than the value As the load increases when pressing the screw against the object to be fastened and drilling a hole, the amount of movement of the driver bit decreases, so as to follow this, It is a fastening tool that reduces the output of the motor.

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

Effect of the Invention

[0012] In the present invention, based on the states of the motor that moves the bit holding part in the axial direction and the first motor that rotates the bit holding part, the moving speed of the bit holding part can be controlled.

Brief Description of the Drawings

[0013] [Figure 1A] It is a side cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. [Figure 1B] It is a top cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. [Figure 1C] It is an exploded perspective view showing an example of the internal structure of the fastening tool of the present embodiment. [Figure 2A] It is a perspective view showing an example of the main part configuration of the fastening tool of the present embodiment. [Figure 2B] It is a perspective view showing an example of the main part configuration of the fastening tool of the present embodiment. [Figure 3A] It is a cross-sectional perspective view showing an example of the main part configuration of the fastening tool of the present embodiment. [Figure 3B] It is a cross-sectional perspective view showing an example of the main part configuration of the fastening tool of the present embodiment. [Figure 4]This is a perspective view showing an example of the screw feed section and nose section of this embodiment. [Figure 5] This is a block diagram showing an example of a fastening tool in this embodiment. [Figure 6] This is a perspective view showing an example of the settings section. [Figure 7A] This flowchart shows an example of the operation of the fastening tool in this embodiment. [Figure 7B] This flowchart shows an example of the operation of the fastening tool in this embodiment. [Figure 8A] This graph shows the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. [Figure 8B] This graph shows the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. [Figure 9A] This is a cross-sectional view showing the tightened state of the screw. [Figure 9B] This is a cross-sectional view showing the tightened state of the screw. [Figure 9C] This is a cross-sectional view showing the tightened state of the screw. [Figure 10A] This flowchart shows another example of the operation of the fastening tool of this embodiment. [Figure 10B] This flowchart shows another example of the operation of the fastening tool of this embodiment. [Figure 11A] This graph shows the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. [Figure 11B] This graph shows the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. [Figure 11C] This graph shows the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. [Figure 12A] This flowchart shows another example of the operation of the fastening tool of this embodiment. [Figure 12B] This flowchart shows another example of the operation of the fastening tool of this embodiment. [Figure 13] This graph shows the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the fastening tool of the present invention will be described with reference to the drawings.

[0015] <Example of fastening tool configuration in this embodiment> Figure 1A is a side cross-sectional view showing an example of the internal structure of the fastening tool of this embodiment, Figure 1B is a top cross-sectional view showing an example of the internal structure of the fastening tool of this embodiment, and Figure 1C is an exploded perspective view showing an example of the internal structure of the fastening tool of this embodiment.

[0016] The fastening tool 1 of this embodiment includes a bit holding unit 3 that holds a driver bit 2 so that it can rotate and move in the axial direction, 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.

[0017] The fastening tool 1 also includes a screw storage section 6 in which the screws 200 are stored, a screw feeding section 7 (described later) that feeds the screws 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 screws 200 are ejected.

[0018] Furthermore, the fastening tool 1 comprises a tool body 10 and a handle 11. The fastening tool 1 also includes a battery mounting section 13 at the end of the handle 11, to which a battery 12 can be detachably attached.

[0019] The fastening tool 1 has a tool body 10 that extends in one direction along the axial direction of the driver bit 2 indicated by arrows A1 and A2, and a handle 11 that extends in another direction intersecting the extension direction of the tool body 10. 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 the front-back direction. The direction in which the handle 11 extends is the up-down direction. Furthermore, the direction perpendicular to the extension direction of the tool body 10 and the extension direction of the handle 11 is the left-right direction.

[0020] The first drive unit 4 is located at the rear of the tool body 10, on either side of the handle 11. The second drive unit 5 is located at the front of the tool body 10, on the other side of the handle 11.

[0021] The screw storage section 6 houses multiple screws 200 connected by connecting bands, forming spiral-wound connecting screws.

[0022] Figures 2A and 2B are perspective views showing an example of the main components of the fastening tool of this embodiment, and Figures 3A and 3B are cross-sectional perspective views showing an example of the main components of the fastening tool of this embodiment. Next, the bit holding unit 3 and the first drive unit 4 will be described with reference to each of these figures.

[0023] The bit holding unit 3 includes a holding member 30 that detachably holds the driver bit 2, a rotating guide member 31 that supports the holding member 30 so as to be movable in the front-rear direction 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 front-rear direction along the rotating guide member 31, and a biasing member 33 that biases the moving member 32 in the rearward direction indicated by arrow A2.

[0024] The retaining member 30 is composed of a cylindrical member, for example, whose outer diameter is slightly smaller than the inner diameter of the rotating guide member 31 and which is placed inside the rotating guide member 31. The retaining member 30 has an opening 30a at the front end of the driver bit 2 along its axial direction, which matches the cross-sectional shape of the driver bit 2. The retaining member 30 is equipped with a detachable retaining mechanism 30c in the opening 30a for detachably holding the driver bit 2. The opening 30a of the retaining member 30 is exposed to the inside of the rotating guide member 31, and the driver bit 2 is detachably inserted into the opening 30a.

[0025] The attachment / detachment holding mechanism 30c includes a ball 30d exposed within the opening 30a and a spring 30e that biases the ball 30d in the direction of being exposed within the opening 30a. The spring 30e is made of an annular leaf spring and is fitted around the outer circumference of the holding member 30.

[0026] The attachment and detachment holding mechanism 30c prevents the driver bit 2 from unintentionally coming out of the holding member 30 by having a ball 30d biased by a spring 30e fit into the groove of the driver bit 2. Furthermore, if a force greater than a predetermined amount is applied in the direction of removing the driver bit 2 from the holding member 30, the ball 30d retracts while the annular spring 30e deforms, making it possible to remove the driver bit 2 from the holding member 30.

[0027] The rotating guide member 31 extends along the extension direction of the tool body 10, that is, along the front-to-back direction indicated by arrows A1 and A2 along the axial direction of the driver bit 2. The rotating guide member 31 is cylindrical in shape with a retaining member 30 inside, and its front end is rotatably supported by a front frame 10b provided on the front side of the case 10a that constitutes the exterior of the tool body 10, via a bearing 34a, which is an example of a bearing. The rear end of the rotating guide member 31 is connected to the first drive unit 4.

[0028] The rotating guide member 31 has grooves 31a formed at two locations on its radially opposing circumferential surface, extending in the front-rear direction as indicated by arrows A1 and A2 along the axial direction of the driver bit 2. The rotating guide member 31 penetrates the holding member 30 radially, and connecting members 30b protruding from both sides of the holding member 30 enter the grooves 31a, thereby connecting the rotating guide member 31 to the holding member 30 via the connecting members 30b.

[0029] The connecting member 30b is a cylindrical member with an oval cross-section, and its longitudinal direction is aligned with the extension direction of the groove 31a, which is parallel to the axial direction of the driver bit 2 indicated by arrows A1 and A2. The transverse direction of the oval shape of the connecting member 30b is perpendicular to the extension direction of the groove 31a indicated by arrows B1 and B2, that is, aligned with the rotation direction of the rotating guide member 31. Furthermore, the width of the connecting member 30b in the transverse direction, that is, the width along the rotation direction of the rotating guide member 31, is configured to be slightly smaller than the width of the groove 31a along the same direction.

[0030] As a result, the connecting member 30b, which is placed in the groove 31a, is supported in the groove 31a so as to be movable along the axial direction of the rotating guide member 31. Furthermore, the movement of the connecting member 30b along the rotational direction relative to the rotating guide member 31 is restricted between one side and the other side of the groove 31a along the direction in which the groove 31a extends. Therefore, as the rotating guide member 31 rotates, the connecting member 30b is pushed against one side or the other side of the groove 31a depending on the rotational direction of the rotating guide member 31, and receives a circumferential force from the rotating guide member 31 that is in the rotational direction.

[0031] Therefore, when the rotating guide member 31 rotates, the connecting member 30b of the holding member 30 is pushed into the groove 31a of the rotating guide member 31, causing the holding member 30 to rotate together with the rotating guide member 31. In addition, the holding member 30 moves in the front-rear direction along the axial direction of the driver bit 2, with the connecting member 30b being guided by the groove 31a of the rotating guide member 31.

[0032] The movable member 32 includes a first movable member 32a that rotates together with the holding member 30 and moves the holding member 30 in the front-rear direction along the rotation guide member 31, a second movable member 32c that is supported by the first movable member 32a via a bearing 32b and pushes the first movable member 32a via the bearing 32b, and a cushioning member 32d attached to the rear side of the second movable member 32c.

[0033] The first movable member 32a is composed of, for example, a cylindrical member whose inner diameter is slightly larger than the outer diameter of the rotating guide member 31 and which is placed outside the rotating guide member 31. The first movable member 32a is connected to the holding member 30 via a connecting member 30b that protrudes from the groove 31a of the rotating guide member 31, thereby being supported so as to be movable along the axial direction of the rotating guide member 31.

[0034] The bearing 32b is an example of a bearing, inserted between the outer circumference of the first moving member 32a and the inner circumference of the second moving member 32c. The first moving member 32a constitutes a bearing inner ring retaining member that holds the inner ring of the bearing 32b, and the second moving member 32c constitutes a bearing outer ring retaining member that holds the outer ring of the bearing 32b. In the bearing 32b, the inner ring is supported on the outer circumference of the first moving member 32a so as to be unable to move in the rotational and axial directions, and the outer ring is supported on the inner circumference of the second moving member 32c so as to be unable to move in the rotational and axial directions.

[0035] As a result, the second movable member 32c is connected to the first movable member 32a via the bearing 32b, with its movement in the forward and backward direction along the axial direction restricted. The second movable member 32c also rotatably supports the first movable member 32a via the bearing 32b.

[0036] Therefore, the first moving member 32a is pushed by the second moving member 32c via the bearing 32b when the second moving member 32c moves in the forward and backward direction along the axial direction, and moves together with the second moving member 32c in the forward and backward direction along the axial direction. In addition, the first moving member 32a is rotatable relative to the second moving member 32c, which does not rotate relative to the rotating guide member 31.

[0037] In this example, the biasing member 33 is composed of a coil spring and is placed outside the rotating 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 contacts a spring seat 32f which is positioned 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 in the forward direction indicated by arrow A1, and applies a force to the moving member 32 that pushes it in the backward direction indicated by arrow A2.

[0038] The first drive unit 4 includes a bit rotation motor 40 and a reduction gear 41, which are driven by electricity supplied from the battery 12. The bit rotation motor 40 is an example of the first motor, in which the shaft 40a of the bit rotation motor 40 is connected to the reduction gear 41, and the shaft 41a of the reduction gear 41 is connected to the rotation guide member 31. In the first drive unit 4, the reduction gear 41 is configured to use planetary gears, and the bit rotation motor 40 is arranged coaxially with the rotation guide member 31 and the holding member 30, and the driver bit 2 held by the holding member 30.

[0039] The first drive unit 4 has a bit rotation motor 40 and a reduction gear 41 mounted on a rear frame 10c provided on the rear side of the case 10a of the tool body 10, and the shaft 41a of the reduction gear 41 is supported on 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 reduction gear 41, and the shaft 41a is supported on the rear frame 10c via a bearing 42, so that it is rotatably supported via the bearing 42, which is an example of a bearing.

[0040] The bit holder 3 and the first drive unit 4 are assembled as a single unit by connecting the front frame 10b and the rear frame 10c with a connecting member 10d that extends in the front-rear direction, and the front frame 10b is fixed to the case 10a of the tool body 10 with screws 10e.

[0041] Furthermore, the bit holder 3 is supported by a bearing 34a at the front end of the rotating guide member 31, which is fixed to the front of the case 10a of the tool body 10, and by a shaft 41a and bearing 42 of the reduction gear 41 at the rear end of the rotating guide member 31, which is fixed to the rear of the case 10a. Thus, the bit holder 3 is rotatably supported by the rotating guide member 31 on the tool body 10.

[0042] As a result, the first drive unit 4 rotates the rotating guide member 31 using the bit rotation motor 40. The holding member 30, which holds the driver bit 2, rotates together with the rotating guide member 31 as the connecting member 30b is pressed against the groove 31a of the rotating guide member 31.

[0043] The bit holder 3 is provided with a guide member 32g on the second movable member 32c. The second movable member 32c is movable in the forward and backward directions indicated by arrows A1 and A2 along the axial direction of the driver bit 2, as the guide member 32g is guided by the coupling member 10d, and its rotation following the rotation guide member 31 is restricted.

[0044] Next, the second drive unit 5 will be described with reference to the figures. The second drive unit 5 comprises a bit moving motor 50 and a reduction gear 51, which are powered by electricity supplied from the battery 12. The bit moving motor 50 is an example of a second motor, in which the shaft 50a of the bit moving motor 50 is connected to the reduction gear 51, and the shaft 51a of the reduction gear 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 positioned along the extension direction of the handle 11.

[0045] The second drive unit 5 has one end of a linear wire 54, which is an example of a transmission member, connected to a pulley 52, and as the pulley 52 rotates, the wire 54 is wound around the pulley 52. ​​The other end of the wire 54 is connected to a wire connection part 32h provided on the second moving member 32c of the moving member 32.

[0046] As a result, the second drive unit 5 rotates the pulley 52 with the bit moving motor 50 and winds up the wire 54, thereby moving the second moving member 32c in the forward direction indicated by arrow A1. When 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 along the axial direction together with the second moving member 32c. When the first moving member 32a moves forward, the holding member 30, which is 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 arrow A1.

[0047] The second drive unit 5 is positioned offset to one side of the approximate center of the fastening tool 1 in the left-right direction, such that the tangential direction of the portion of the pulley 52 around which the wire 54 is wound aligns with the extending direction of the rotating guide member 31. Furthermore, the diameter of the pulley 52 is set such that the wire 54 is not wound on multiple times when the pulley 52 winds the wire 54 in order to move the driver bit 2 by a predetermined amount.

[0048] As a result, the relationship between the rotation amount of the bit movement motor 50 and the movement amount of the holding member 30 becomes a one-to-one relationship throughout the entire movable range of the holding member 30, and by controlling the rotation amount of the bit movement motor 50, the movement amount of the holding member 30 along the axial direction of the rotating guide member 31 can be controlled. In other words, by controlling the rotation amount of the bit movement motor 50, the movement amount of the driver bit 2 attached to the holding member 30 can be controlled.

[0049] Furthermore, the movement speed of the driver bit 2 can be increased according to the rotation speed of the bit movement motor 50. Therefore, the time required to press the screw 200 against the object to be fastened with the driver bit 2 can be shortened.

[0050] Furthermore, since the wire 54 is flexible enough to be wound onto the pulley 52, it cannot push the second moving member 32c to move the moving member 32 backward. Therefore, a biasing member 33 is provided that compresses the moving member 32 when it moves forward as indicated by arrow A1, and applies a force to the moving member 32 that pushes it backward as indicated by arrow A2. In this configuration, the wire 54 is wound onto the pulley 52, and the driver bit 2 is advanced, and then the driver bit 2 can be moved backward after it has advanced.

[0051] Figure 4 is a perspective view showing an example of the screw feed section and nose section of this embodiment. Next, the screw feed section 7 and nose section 8 will be described with reference to each figure. The screw feed section 7 comprises a screw feed motor 70, a pinion gear 71 attached to the shaft of the screw feed motor 70 via a reduction gear, 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 a connecting screw fed from the screw storage section 6.

[0052] In the screw feeding section 7, a rack gear 72 is supported so as to be movable in the vertical direction along the feeding direction of the connecting screw. In the screw feeding section 7, the screw feeding motor 70 rotates in forward and reverse directions, causing the engaging portion 73 that engages with the connecting screw to reciprocate in the vertical direction, thereby feeding the connecting screw. Alternatively, the screw feeding section 7 may be configured to reciprocate the engaging portion 73 by a drive unit that moves linearly using a combination of electromagnetic force and biasing means, such as a solenoid.

[0053] The nose section 8 is supplied with a screw 200 by the screw feeding section 7 and has an injection passage 80 through which the driver bit 2 passes. The nose section 8 also has an injection port 81a that communicates with the injection passage 80 and includes a contact member 81 that contacts the object to be fastened. Furthermore, the nose section 8 includes a contact arm 82 that moves in the front-rear direction in conjunction with the contact member 81.

[0054] In the nose section 8, the contact member 81 is supported so as to be movable in the front-rear direction indicated by arrows A1 and A2, and the contact arm 82 moves in the front-rear direction in conjunction with the contact member 81. In the nose section 8, the contact member 81 is biased forward by a biasing member (not shown), and the contact member 81, which has moved backward when pressed against the object to be fastened, is then biased forward by the biasing member and moves forward.

[0055] 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 activated or deactivated when it is pressed by the contact arm 82, which moves backward as the contact member 81 is pressed against the object to be fastened and the contact arm 82 moves backward. In this example, the state in which the contact switch unit 84 is not activated because it is not being pressed by the contact arm 82 is defined as the contact switch unit 84 being off, and the state in which the contact switch unit 84 is activated because it is being pressed by the contact arm 82 is defined as the contact switch unit 84 being on.

[0056] Figure 5 is a block diagram showing an example of a fastening tool according to this embodiment. Next, the configuration of the control and operation of the fastening tool 1 will be described with reference to each figure.

[0057] The fastening tool 1 includes a trigger 9 that receives operation and a trigger switch unit 90 that is activated by the operation of the trigger 9. As shown in Figure 1A and other figures, the trigger 9 is located on the front side of the handle 11 and is configured to be operable with the fingers of the hand gripping the handle 11. The trigger switch unit 90 is activated when pressed by the trigger 9.

[0058] The trigger switch unit 90 is switched on or off when pressed by the trigger 9. In this example, when the trigger 9 is not operated and the trigger switch unit 90 is not pressed by the trigger 9, the trigger switch unit 90 is considered off, and when the trigger 9 is operated and the trigger switch unit 90 is activated by being pressed by the trigger 9, the trigger switch unit 90 is considered on.

[0059] The fastening tool 1 includes a control unit 100 that controls a first drive unit 4, a second drive unit 5, and a screw feed unit 7 based on the output of a trigger switch unit 90 that is operated by the operation of a trigger 9 and a contact switch unit 84 that is operated by being pressed by a contact member 81. The control unit 100 is made up of a circuit board on which various electronic components are mounted, and as shown in Figure 1A, it is housed in a circuit board housing unit 111 provided on the back side of the screw storage unit 6, between the screw storage unit 6 and the handle 11.

[0060] The control unit 100 controls whether the bit moving motor 50 of the second drive unit 5 and the bit rotating motor 40 of the first drive unit 4 are driven, based on the combination of the on / off states of the contact switch unit 84 and 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 fastening the screw 200 engaged with the driver bit 2 to the object to be fastened. The control unit 100 also includes a first motor state detection unit that detects the state of the bit rotating motor 40 and controls the movement speed of the bit holding unit 3 based on the state of the bit rotating motor 40 when fastening the screw 200 engaged with the driver bit 2 to the object to be fastened. The motor state detection unit and the first motor state detection unit may also be configured to have detection units that detect the rotation speed (rotational speed) of the bit moving motor 50 and bit rotating motor 40 independently of the control unit 100.

[0061] As described above, the fastening tool 1 includes a first drive unit 4 that rotates the driver bit 2, which is held by the holding member 30 in the bit holding unit 3, by the drive of the bit rotation motor 40. The fastening tool 1 also includes a second drive unit 5 that moves the driver bit 2, which is held by the holding member 30 in the bit holding unit 3, in the forward and backward directions along the axial direction by the drive of the bit movement motor 50.

[0062] In the fastening tool 1, the bit movement motor 50 rotates in a predetermined direction, causing the driver bit 2, held by the holding member 30 in the bit holding section 3, to move forward (advance) in the direction indicated by arrow A1. Also, in the fastening tool 1, the bit rotation motor 40 rotates in a predetermined direction, causing the driver bit 2 to rotate in the direction for fastening the screw 200.

[0063] The fastening tool 1 advances the driver bit 2 by rotating the bit moving motor 50, 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.

[0064] Furthermore, the fastening tool 1 fastens the screw 200, which is engaged with the driver bit 2, to the object to be fastened by rotating the driver bit 2 in the direction of fastening the screw 200 using the rotation of the bit rotation motor 40.

[0065] Furthermore, the fastening tool 1 rotates the bit moving motor 50 in conjunction with the rotation of the bit rotating motor 40, thereby advancing the driver bit 2 in accordance with the fastening of the screw 200.

[0066] Therefore, the control unit 100 controls the amount of movement (advance movement) of the driver bit 2 by controlling the amount of rotation of the bit movement motor 50. By controlling the amount of movement of the driver bit 2, the control unit 100 controls the stopping position of the driver bit 2 along its axial direction.

[0067] Furthermore, the control unit 100 advances the driver bit 2 in accordance with the tightening of the screw 200 by controlling the rotation speed of the bit rotation motor 40 and the rotation speed of the bit movement motor 50.

[0068] When the bit rotation motor 40 rotates the driver bit 2 in the direction of fastening the screw 200, the screw 200 engaged with the driver bit 2 is tightened into the object to be fastened, causing the screw 200 to move (advance) along the axial direction. The amount of axial movement (movement speed) of the screw 200 due to the rotation of the screw 200 is estimated from the lead angle of the screw 200 and the amount and speed of rotation of the bit rotation motor 40.

[0069] The control unit 100 rotates the bit movement motor 50 at a predetermined rotational 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.

[0070] The fastening tool 1 moves the screw 200 forward and presses it against the object to be fastened, causing the tip of the screw 200 to drill a hole in the surface of the object. However, if the object to be fastened is a steel plate, it is more difficult to drill a hole compared to when the object to be fastened is wood or plaster. When the operation to drill a hole in an object to be fastened that is difficult to drill, such as a steel plate, begins by moving the screw 200 forward, the screw 200 is difficult to advance until a hole is drilled in the steel plate and the part of the screw 200 with threads has reached the steel plate, so the load on the driver bit 2 in the axial direction increases. When the load on the driver bit 2 in the axial direction increases when the screw 200 is advanced to drill a hole in the object to be fastened, the reaction force of the force that the driver bit 2 exerts on the object to be fastened via the screw 200 increases, and there is a possibility that the fastening tool 1 will lift away from the object to be fastened.

[0071] Therefore, when the object to be fastened is a steel plate, for example, when the bit moving motor 50 moves the screw 200 forward to drill a hole in the object to be fastened with the screw 200, the control unit 100 controls the rotation speed of the bit moving motor 50 when the load on the driver bit 2 in the axial direction is high, thereby suppressing the fastening tool 1 from lifting up due to the reaction force of the force with which the driver bit 2 pushes the object to be fastened via the screw 200.

[0072] In other words, the fastening tool 1 presses the tip of the screw 200 against the object to be fastened by moving the driver bit 2 axially (advancing it). However, in the case of fastening objects that are difficult to drill holes in, such as steel plates, the axial load on the driver bit 2 increases, making it difficult for the screw 200 to advance, thus increasing the load when moving the driver bit 2 axially (advancing it). For this reason, when drilling holes in fastening objects that are difficult to drill, such as steel plates, with the screw 200, the amount of axial movement (advancement) of the driver bit 2 decreases compared to when the screw 200 is fastened to normal fastening objects such as wood or plaster.

[0073] As the amount of axial movement (advance) of the driver bit 2 decreases, the rotational speed of the bit movement motor 50 decreases. Therefore, when drilling holes in fastening objects that are difficult to drill, such as steel plates, by advancing the screw 200 and pressing it against them, the decrease in the rotational speed of the bit movement motor 50 is greater compared to when fastening screws 200 to ordinary fastening objects such as wood or plaster.

[0074] On the other hand, in the case of fastening objects that are difficult to puncture, such as steel plates, the screw 200 will spin freely until its tip punctures the steel plate. As a result, the load on the driver bit 2 in the rotational direction is reduced, and the rotational speed of the bit rotation motor 40 does not decrease compared to the case where the tip of the screw 200 punctures the fastening object and is then tightened into the object.

[0075] In this manner, as 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 in accordance with the changes in the load applied to the driver bit 2 in the axial direction and the changes in the load applied to the driver bit 2 in the rotational direction.

[0076] The fastening tool 1 determines whether or not it is drilling a hole in a fastening target object that is difficult to drill, such as a steel plate, and controls the bit movement motor 50 according to the fastening target object. The fastening tool 1 is equipped with a load detection unit 112 that detects changes in the load applied to the driver bit 2 in the axial direction, or changes in the load applied to the driver bit 2 in the rotational direction, or changes in the load applied to the driver bit 2 in both the axial and rotational directions, as the screw 200 engaged with the driver bit 2 is advanced to drill a hole in the fastening target object.

[0077] In the operation of fastening the screw 200 to the object to be fastened by rotating the driver bit 2 and moving it in the axial direction, both the load on the driver bit 2 in the axial direction and the load on the driver bit 2 in the rotational direction increase, causing the rotational speed of the bit movement motor 50 and the rotational speed of the bit rotation motor 40 to decrease.

[0078] However, in the operation of advancing the screw 200 engaged with the driver bit 2 to drill a hole in the object to be fastened, when drilling a hole in an object that is difficult to drill, such as a steel plate, the decrease in the rotational speed of the bit moving motor 50 increases due to the increased load on the driver bit 2 in the axial direction. On the other hand, when drilling a hole in an object that is difficult to drill, such as a steel plate, the screw 200 rotates freely, so the decrease in the rotational speed of the bit rotating motor 40 decreases due to the reduced load on the driver bit 2 in the rotational direction.

[0079] Therefore, the load detection unit 112 detects predetermined changes in the load applied to the driver bit 2 in the axial direction and / or the load applied to the driver bit 2 in the rotational direction, based on changes in the rotational speed of the bit moving motor 50 and / or the bit rotating motor 40.

[0080] The load detection unit 112 detects a predetermined load equivalent to drilling a hole in a fastening object that is difficult to drill, such as a steel plate, by advancing the screw 200, based on a predetermined increase in the decrease in the rotational speed of the bit moving motor 50, or a predetermined decrease in the decrease in the rotational speed of the bit rotating motor 40.

[0081] Based on a predetermined load detected by the load detection unit 112, if the control unit 100 determines that it is advancing the screw 200 to drill a hole in a fastening target object that is difficult to drill, such as a steel plate, it switches from a first load control, which drives the bit movement motor 50 with a first output corresponding to the tightening of the screw 200 into a normal fastening target object such as wood or plaster, to a second load control, which drives the bit movement motor 50 with a second output corresponding to the increased load when advancing the screw 200 to drill a hole in a fastening target object that is difficult to drill, such as a steel plate. In the second load control, the control unit 100 limits the current flowing to the bit movement motor 50 and reduces the output of the bit movement motor 50, in this case the rotation speed.

[0082] As the load increases due to advancing the screw 200 and pressing it against the object to be fastened, such as a steel plate, the amount of movement (advance) of the driver bit 2 decreases. If the rotation of the bit moving motor 50 is maintained at a rotational speed corresponding to the rotational speed of the bit rotating motor 40, the actual amount of movement (advance) of the driver bit 2 becomes smaller than the axial movement (advance) of the screw 200 being tightened by the rotation of the bit rotating motor 40, i.e., the target amount of movement (advance) of the driver bit 2 due to the rotation of the bit moving motor 50. As a result, the fastening tool 1 lifts up due to the reaction force of the force with which the driver bit 2 pushes the object to be fastened via the screw 200.

[0083] Therefore, in the second load control, the rotational speed of the bit movement motor 50 is reduced to the extent that it follows the decrease in the amount of movement (advance) of the driver bit 2 as the load increases in pressing the screw 200 against the object to be fastened and drilling a hole. As a result, the target amount of movement (advance) of the driver bit 2 due to the rotation of the bit movement motor 50 and the actual amount of movement (advance) of the driver bit 2 become approximately equal, the generation of a reaction force from the force with which the driver bit 2 presses against the object to be fastened via the screw 200 is suppressed, and the fastening tool 1 is prevented from lifting up.

[0084] The control unit 100 switches from the first load control to the second load control based, for example, on a change in the rotational speed of the bit movement motor 50.Therefore, the control unit 100 sets a high load deceleration threshold, which corresponds to the amount of decrease in the rotational speed of the bit movement motor 50 due to the increase in the axial load on the driver bit 2, as a threshold for determining whether or not it is performing the operation of advancing the screw 200 to drill a hole in a fastening target object such as a steel plate that is difficult to drill.

[0085] The high-load deceleration threshold may be set based on the rotational speed of the bit movement motor 50. In this case, if the rotational speed of the bit movement motor 50 falls below the high-load deceleration threshold during the execution of the first load control, the control unit 100 switches to the second load control described above.

[0086] Furthermore, the high-load deceleration threshold may be set by the difference between the target amount of driver bit 2 movement, which is determined from the rotational speed of the bit movement motor 50, and the actual amount of driver bit 2 movement. In this case, if the control unit 100, during the execution of the first load control, finds that the difference between the target amount of driver bit 2 movement and the actual amount of driver bit 2 movement is greater than or equal to the high-load deceleration threshold, it switches to the second load control described above. The target amount of driver bit 2 movement may be obtained from the axial movement of the screw 200 that is tightened by the rotation of the bit rotation motor 40.

[0087] Furthermore, the high-load deceleration threshold may be set as the 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, during the execution of the first load control, 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 predetermined sampling intervals, integrates the difference if it is greater than or equal to a predetermined threshold, and switches to the second load control described above if the integrated value of the difference greater than or equal to the high-load deceleration threshold.

[0088] During the execution of the second load control described above, the control unit 100 performs a drilling control to drill holes in fastening targets that are difficult to puncture, such as steel plates.

[0089] During drilling control while the second load control is being executed, if the control unit 100 determines that the rotational speed of the bit movement motor 50 is not increasing and is below a specified value, it increases the current supplied to the bit movement motor 50 from the current value limited by the second load control. In other words, if the control unit 100 detects for a predetermined number of consecutive times at a predetermined sampling interval that the rotational speed of the bit movement motor 50 is not increasing and the actual amount of movement of the driver bit 2 is below a specified value, for example, that the actual amount of movement of the driver bit 2 is zero, it increases the output of the bit movement motor 50, in this case the rotational speed, to gradually increase the amount of movement (advance) of the driver bit 2 along the axial direction.

[0090] When the screw 200 drills a hole in a fastening object that is difficult to pierce, such as a steel plate, the resistance to the screw 200's forward movement decreases, reducing the load on the bit movement motor 50 and increasing the rotational speed of the bit movement motor 50. If the control unit 100 determines that the rotational speed of the bit movement motor 50 is above a specified value during the 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 movement motor 50.

[0091] The fastening tool 1 includes a setting unit 110 in which the rotation amount of the bit moving motor 50 that defines the forward movement amount of the driver bit 2 is set. Figure 6 is a perspective view showing an example of the setting unit, and the setting unit 110 will now be described with reference to each figure.

[0092] The setting unit 110 is an example of a setting means, and is configured to allow selection of any setting value from a plurality of setting values, or to allow stepless selection of any setting value.

[0093] In this example, the setting unit 110 is configured such that the setting value is selected by an operation unit 110a consisting of buttons. Alternatively, the operation unit 110a may be configured such that the setting value is selected by a rotary dial. Furthermore, the setting unit 110 may be configured to display the selected setting value so that the operator can easily understand the current setting value, for example by indicating the current value with a label or engraving, or by indicating the current value with a display unit 110b such as an LED. The contents displayed on the display unit 110b include the setting value of the screw depth defined by the amount the driver bit 2 advances, as well as the ON / OFF status of the power supply, the operating mode selected from the various selectable operating modes, the presence or absence of screws, the remaining amount of screws, and whether or not there is an abnormality.

[0094] The setting section 110 is provided on both the left and right sides of the surface facing the handle 11 in the circuit board storage section 111, which is located on the back side of the screw storage section 6.

[0095] This makes it possible to see the setting section 110 from both the left and right sides of the handle 11 when viewing the fastening tool 1 from the rear.

[0096] <Example of operation of the fastening tool in 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 fastened state of the screw. Next, an example of the fastening operation of the fastening tool of this embodiment will be described with reference to each of these figures.

[0097] In its standby state, as shown in Figure 1A, the fastening tool 1 has the tip of the driver bit 2 positioned at a standby position P1 behind the injection passage 80, allowing it to supply screws 200 to the injection passage 80.

[0098] In step SA1 of Figure 7A, the control unit 100 sets the rotation amount of the bit movement motor 50 that defines the amount of forward movement of the driver bit 2, based on the setting value selected in the setting unit 110. When the contact member 81 is pressed against the object to be fastened 202, and the contact arm 82 presses the contact switch unit 84, 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 movement motor 50 of the second drive unit 5 in step SA5 to perform the first load control.

[0099] When the bit moving motor 50 is driven and rotates in the forward direction, which is one direction, the pulley 52 rotates in the forward direction, causing the wire 54 to be wound onto the pulley 52. ​​As the wire 54 is wound onto the pulley 52, the second moving member 32c, which is connected to the wire 54, is guided by the rotating guide member 31 and moves forward along the axial direction. As 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 together with the second moving member 32c, it moves forward along the axial direction while compressing the biasing member 33.

[0100] When the first movable member 32a moves forward, the holding member 30, which is connected to the first movable 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 31a of the rotating guide member 31.

[0101] As a result, the driver bit 2 held by the retaining member 30 moves forward in the direction indicated by arrow A1, engages with the screw 200 supplied to the nozzle 81a of the nose portion 8, moves the screw 200 forward, and presses it against the object to be fastened 202.

[0102] Furthermore, when the bit rotation motor 40 is driven and rotates in the positive direction, the rotation guide member 31 rotates in the positive direction. When the rotation guide member 31 rotates in the positive direction, the connecting member 30b, which is connected to the holding member 30, is pressed against the groove 31a of the rotation guide member 31, causing the holding member 30 to rotate together with the rotation guide member 31.

[0103] 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, in conjunction with the operation of the first drive unit 4 to rotate the driver bit 2 and tighten the screw into the object to be fastened 202, 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 tightened into the object to be fastened 202.

[0104] Figure 8A shows the relationship between the rotation speeds of the bit rotation motor 40 and the bit movement motor 50 when a screw 200 is fastened to a normal fastening target 202 such as wood or plaster, and Figure 8B shows the relationship between the rotation speeds of the bit rotation motor 40 and the bit movement motor 50 when a fastening target 202 such as plaster is placed on a steel plate 203 and the screw 200 is fastened to the steel plate 203.

[0105] When the driver bit 2 is rotated to begin the operation of tightening the screw 200 into the object to be fastened 202, 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, both the rotation speed V1 of the bit rotation motor 40 and the rotation speed V2 of the bit movement motor 50 decrease. However, the load on the driver bit 2 via the screw 200 differs depending on whether the screw 200 is fastened to a normal object to be fastened 202 such as wood or plaster, or whether 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 to the steel plate 203.

[0106] In particular, in the case of steel plates 203 that are difficult to drill, as shown in Figure 9A, when the tip of the screw 200 reaches the steel plate 203, the load when pressing the screw 200 against the steel plate 203 is greater than when using wood or plaster, and the load when moving (advancing) the driver bit 2 in the axial direction becomes greater. As a result, the decrease in the rotational speed V2 of the bit movement motor 50 is greater when fastening the screw 200 to a steel plate 203 as shown in Figure 8B compared to when fastening the screw 200 to a normal fastening target object 202 such as wood or plaster as shown in Figure 8A.

[0107] Therefore, in step SA7, the control unit 100 compares the rotational speed V2 of the bit movement motor 50 with the high-load deceleration threshold S to determine whether the amount of reduction in the rotational speed of the bit movement motor 50 is within the range of normal deceleration.

[0108] As the rotational speed V2 of the bit moving motor 50 decreases after the load generation timing T1, the control unit 100 determines that, as shown in Figure 8A, the rotational speed V2 of the bit moving motor 50 does not fall below the high-load deceleration threshold S and that the amount of decrease in the rotational speed of the bit moving motor 50 is within the range of normal deceleration, and determines that the screw 200 is being fastened to a normal fastening target 202 such as wood or plaster, and continues the first load control.

[0109] When the control unit 100 determines in step SA8 that the rotation amount of the bit movement 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 by the specified amount as shown in Figure 8A, it stops driving the bit rotation motor 40 in step SA9, stops the rotation of the bit movement motor 50 in the forward direction in step SA10, and then reverses the bit movement motor 50 in step SA11.

[0110] When the bit moving motor 50 rotates in the opposite direction, the pulley 52 rotates in the opposite direction, causing the wire 54 to be pulled out from the pulley 52. ​​As 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 backward.

[0111] The second moving member 32c is pushed backward by the biasing member 33, guided by the rotating guide member 31, and moves backward along the axial direction. As the second moving member 32c moves backward, the first moving member 32a is pulled by the second moving member 32c via the bearing 32b, and moves backward along the axial direction together with the second moving member 32c.

[0112] When the first movable member 32a moves in the rearward direction, the holding member 30, which is connected to the first movable member 32a by the connecting member 30b, moves in the rearward direction along the axial direction of the driver bit 2, with the connecting member 30b being guided by the groove 31a of the rotating guide member 31.

[0113] In step SA12, the control unit 100 reverses the bit movement motor 50 to the initial position where a predetermined amount of wire 54 is pulled out from the pulley 52. ​​Once the holding member 30 and the moving member 32 have moved backward to the 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 movement motor 50 in step SA13.

[0114] 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 engagement portion 73. When the engagement portion 73 has lowered to a position where it engages with the next screw 200, the control unit 100 reverses the screw feed motor 70 to raise the engagement portion 73 and supply the next screw 200 to the injection passage 80.

[0115] In step SA7, the control unit 100 compares the rotational speed V2 of the bit movement motor 50 with the high-load deceleration threshold. As shown in Figure 8B, if the control unit 100 determines that the rotational speed V2 of the bit movement motor 50 is below the high-load deceleration threshold S and that the reduction in the rotational speed of the bit movement motor 50 is greater than or equal to the normal deceleration range, 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 movement motor 50, thereby reducing the output of the bit movement motor 50, in this case, its rotational speed. Thus, the timing T2 for starting current limiting is when the rotational speed V2 of the bit movement motor 50 falls below the high-load deceleration threshold S.

[0116] While the control unit 100 is performing a second load control operation, which involves limiting the rotation speed of the bit moving motor 50 and continuing the rotation of the bit rotating motor 40, it performs a drilling control operation to drill holes in the steel plate 203.

[0117] During the drilling section E1 in which drilling control is performed while the second load control is being executed, the control unit 100 detects the rotational speed of the bit movement motor 50 at a predetermined sampling interval, and at timing T3, which determines whether or not to relax the current limit as shown in Figure 8B, it determines whether or not the rotational speed of the bit movement motor 50 is equal to or greater than the specified value for releasing the second load control.

[0118] If the control unit 100 determines in step SA15 that the rotational speed of the bit movement motor 50 has not reached the specified value for releasing the second load control, in step SA16, it increases the current supplied to the bit movement motor 50 from the current value limited by the second load control. By increasing the current supplied to the bit movement motor 50, the output of the bit movement motor 50, in this case its rotational speed, is increased, gradually increasing the amount of movement (advance movement) of the driver bit 2 along the axial direction.

[0119] This gradually increases the force with which the screw 200 is pressed against the object to be fastened via the driver bit 2, while suppressing the increase in the reaction force of the force with which the driver bit 2 presses against the object to be fastened via the screw 200, making it easier to drill a hole in the steel plate 203, as shown in Figure 9B.

[0120] In step SA15, the control unit 100 determines that the rotational speed of the bit movement motor 50 is equal to or greater than the specified value for releasing the second load control. In step SA17, it switches from the second load control to the first load control and releases the current limit to the bit movement motor 50 at the timing T4 shown in Figure 8B.

[0121] In other words, as shown in Figure 9C, when the screw 200 drills a hole in the steel plate 203, the screw 200 is able to move axially (advance), and the load on the driver bit 2 when it moves axially (advance) decreases. As a result, the amount of axial movement of the driver bit 2 can follow the amount of axial movement of the screw 200 when the screw 200 rotates and is tightened into the steel plate 203, and the rotational speed of the bit movement motor 50 increases. Therefore, by releasing the limit on the current flowing to the bit movement motor 50, in the screw tightening section E2, the driver bit 2 can be made to follow the screw 200 as it is tightened into the object to be fastened 202 and the steel plate 203, and the screw 200 can be tightened into the object to be fastened 202 and the steel plate 203.

[0122] In addition, during the drilling section E1 in which drilling control is performed while the second load control is being executed, the control unit 100 may detect the rotational speed of the bit moving motor 40 at a predetermined sampling interval and, at timing T3 in which it is determined whether or not to relax the current limit as shown in Figure 8B, determine whether the decrease in the amount of decrease in the rotational speed of the bit rotating motor 40 is greater than or equal to the specified value for releasing the second load control of the bit moving motor 50. In the drilling section E1 in which drilling control is performed while the second load control is being executed, as shown by the dashed line in Figure 8B, after the screw 200 spins freely and the decrease in the rotational speed of the bit rotating motor 40 decreases, the decrease in the rotational speed of the bit rotating motor 40 may increase again due to an increase in load, such as when a hole begins to be drilled in the steel plate 203. Therefore, if the control unit 100 determines that the decrease in the amount of decrease in the rotational speed of the bit rotating motor 40 has increased and is greater than or equal to the specified value for releasing the second load control of the bit moving motor 50, it increases the current supplied to the bit moving motor 50 from the current value limited by the second load control.

[0123] Even when tightening screws 200 into steel plate 203, the subsequent operation is the same as with normal fastening objects. In step SA8, the control unit 100 determines that the amount of rotation of the bit movement 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 by the specified amount as shown in Figure 8B, the control unit 100 stops driving the bit rotation motor 40 in step SA9, stops the rotation of the bit movement motor 50 in the forward direction in step SA10, and then reverses the bit movement motor 50 in step SA11.

[0124] In step SA12, when the holding member 30 and the moving member 32 have moved backward to the 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.

[0125] Figures 10A and 10B are flowcharts showing other examples of the operation of the fastening tool of this embodiment, and Figures 11A, 11B, and 11C are graphs showing the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. Next, other examples of the fastening operation of the fastening tool of this embodiment will be described with reference to each figure. In other examples of fastening operation, the fastening tool 1, which switches between the first load control and the second load control described above, is configured in the setting unit 110 to switch between a first control mode, which performs the second load control regardless of the magnitude of the load applied to the driver bit 2 in the axial direction, and a second control mode, which performs the second load control according to the magnitude of the load applied to the driver bit 2 in the axial direction. For this reason, 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 the steel plate mode.

[0126] In step SB1 of Figure 10A, the fastening tool 1 is configured by the setting unit 110 to determine whether or not to execute the first control mode and the second control mode.

[0127] In step SB2, the control unit 100 sets the rotation amount of the bit movement motor 50 that defines the amount of forward movement of the driver bit 2, based on the setting value selected in the setting unit 110. In step SB3, the contact switch unit 84 is turned on, and in step SB4, the trigger switch unit 90 is turned on. In step SB5, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4, and in step SB6, the bit movement motor 50 of the second drive unit 5.

[0128] When the bit movement motor 50 is driven and rotates in the forward direction, which is one direction, the driver bit 2 held by the holding member 30 of the bit holding part 3 moves forward in the direction indicated by arrow A1, engages with the screw 200 supplied to the nozzle 81a of the nose part 8, moves the screw 200 forward, and presses it against the object to be fastened.

[0129] Furthermore, when the bit rotation motor 40 is driven and rotates in the forward direction, which is one 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 tightens 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 tighten 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 tightened into the object to be fastened.

[0130] When the driver bit 2 is rotated to begin tightening the screw 200 into the object 202, a load is generated on the driver bit 2 via the screw 200. When the control unit 100 detects the load caused by tightening the screw 200 in step SB7, it determines in step SB8 whether or not the execution of the first control mode has been selected.

[0131] When the control unit 100 determines that the execution of the first control mode has been selected, as shown in Figure 11A, it detects the load caused by tightening the screw 200 in step SB7 described above, and determines that the movement speed of the bit holder 3 has decreased when the screw 200 engaged with the driver bit 2 is fastened to the object to be fastened 202. After that, without detecting or determining the magnitude of the load applied in the axial direction of the driver bit 2, the control unit 100 switches from the first load control to the second load control in step SB9. In the second load control, the control unit 100 limits the current flowing to the bit moving motor 50, thereby reducing the output of the bit moving motor 50, in this case, the rotation speed.

[0132] While the control unit 100 is performing a second load control operation, which involves limiting the rotation speed of the bit moving motor 50 and continuing the rotation of the bit rotating motor 40, it performs a drilling control operation to drill holes in the steel plate 203.

[0133] During the drilling section E1 in which drilling control is performed while the second load control is being executed, the control unit 100 detects the rotational speed of the bit movement motor 50 at a predetermined sampling interval, and at timing T2 in which it is determined whether or not to relax the current limit, it determines whether the rotational speed of the bit movement motor 50 is equal to or greater than the specified value for releasing the second load control.

[0134] If the control unit 100 determines in step SB10 that the rotational speed of the bit movement motor 50 has not reached the specified value for releasing the second load control, in step SB11, it increases the current supplied to the bit movement motor 50 from the current value limited by the second load control. By increasing the current supplied to the bit movement motor 50, the output of the bit movement motor 50, in this case its rotational speed, is increased, gradually increasing the amount of movement (advance movement) of the driver bit 2 along the axial direction.

[0135] This gradually increases the force with which the screw 200 is pressed against the object to be fastened via the driver bit 2, while suppressing the increase in the reaction force of the force with which the driver bit 2 presses against the object to be fastened via the screw 200, making it easier to drill a hole in the steel plate 203.

[0136] In step SB10, if the control unit 100 determines that the rotational speed of the bit movement motor 50 is equal to or greater than the specified value for releasing the second load control, in step SB12, it switches from the second load control to the first load control and releases the current limit to the bit movement motor 50 at timing T3 for releasing the current limit.

[0137] In other words, when the screw 200 drills a hole in the steel plate 203, the screw 200 is able to move (advance) in the axial direction, and the load on the driver bit 2 when it moves (advances) in the axial direction decreases. As a result, the amount of axial movement of the driver bit 2 can follow the amount of axial movement of the screw 200 when the screw 200 rotates and is tightened into the steel plate 203, and the rotational speed of the bit movement motor 50 increases. Therefore, by releasing the limit on the current flowing to the bit movement motor 50, in the screw tightening section E2, the driver bit 2 can be made to follow the screw 200 as it is tightened into the object to be fastened 202 and the steel plate 203, and the screw 200 can be tightened into the object to be fastened 202 and the steel plate 203.

[0138] In step SB13, the control unit 100 determines that the rotation amount of the bit movement 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 by a specified amount, the control unit 100 stops driving the bit rotation motor 40 in step SB14, stops the rotation of the bit movement motor 50 in the forward direction in step SB15, and then reverses the bit movement motor 50 in step SB16.

[0139] In step SB17, when the holding member 30 and the moving member 32 have moved backward to the 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.

[0140] If the control unit 100 determines in step SB8 that the execution of the first control mode has not been selected, in step SB19 it 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. After the load detection timing T1 due to tightening the screw 200, as shown in Figure 11B, if 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, and that the movement speed of the bit holding unit 3 exceeds a predetermined speed when fastening the screw 200 engaged with the driver bit 2 to the object to be fastened 202, 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 to a normal object to be fastened 202 such as wood or plaster, and continues the first load control described above.

[0141] In step SB8, the control unit 100 determines that the execution of the first control mode has not been selected. In step SB19, as shown in Figure 11C, if the rotational speed V2 of the bit moving motor 50 falls below the high-load deceleration threshold S, and the movement speed of the bit holding unit 3 becomes below a predetermined speed when fastening the screw 200 engaged with the driver bit 2 to the object to be fastened 202, and the amount of reduction in the rotational speed of the bit moving motor 50 is greater than or equal to the normal deceleration range, 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, thereby reducing the output of the bit moving motor 50, in this case, the rotational speed.

[0142] Figures 12A and 12B are flowcharts showing other examples of the operation of the fastening tool of this embodiment, and Figure 13 is a graph showing the relationship between the rotational speeds of the bit rotation motor and the bit movement motor. Next, with reference to each figure, 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 angle control is performed at a predetermined timing on the bit rotation motor 40 that rotates the driver bit 2 to increase the rotational speed.

[0143] Lead angle control is specifically achieved by using a motor equipped with a sensor that detects the switching of the rotor magnetic force direction at the normal 30-degree lead angle position, and delaying the power supply switch from the point when a sensor signal that is one commutation unit earlier than the normal power supply state is detected.

[0144] In step SC1, the control unit 100 sets the amount of rotation of the bit movement motor 50 that defines the amount of forward movement of the driver bit 2, based on the setting value selected in the setting unit 110. In step SC2, the contact switch unit 84 is turned on, and in step SC3, the trigger switch unit 90 is turned on. In step SC4, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4, and in step SC5, the bit movement motor 50 of the second drive unit 5.

[0145] The control unit 100 does not perform advance angle control from the start of driving the bit rotation motor 40 until the rotation speed rises to a specified value. This is because performing advance angle control results in a state of weak torque, and if advance angle control is performed immediately after the start of driving, it will take time for the rotation speed to increase.

[0146] When the bit movement motor 50 is driven and rotates in the forward direction, which is one direction, the driver bit 2 held by the holding member 30 of the bit holding part 3 moves forward in the direction indicated by arrow A1, engages with the screw 200 supplied to the nozzle 81a of the nose part 8, moves the screw 200 forward, and presses it against the object to be fastened.

[0147] Furthermore, when the bit rotation motor 40 is driven and rotates in the forward direction, which is one 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 tightens 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 tighten 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 tightened into the object to be fastened.

[0148] When the driver bit 2 is rotated to start the operation of tightening the screw 200 into the object to be fastened 202, a load is generated on the driver bit 2 via the screw 200 in step SC6. When a load is generated on the driver bit 2, the control unit 100, in step SC7, compares the rotational speed V2 of the bit movement motor 50 with the high-load deceleration threshold S to determine whether the amount of decrease in the rotational speed of the bit movement motor 50 is within the range of normal deceleration.

[0149] In step SC7, the control unit 100 compares the rotational speed V2 of the bit moving motor 50 with the high-load deceleration threshold. As shown in Figure 13, if the control unit 100 determines that the rotational speed V2 of the bit moving motor 50 is below the high-load deceleration threshold 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, 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, thereby reducing the output of the bit moving motor 50, in this case, the rotational speed.

[0150] When the control unit 100 switches from the first load control to the second load control, it performs advance angle advance control in step SC9. In the case of fastening objects that are difficult to puncture, such as steel plates, the screw 200 will rotate freely until the tip of the screw 200 punctures the steel plate, so the load on the driver bit 2 in the rotational direction will be low. When advance angle advance control is performed on the bit rotation motor 40 while the load on the bit rotation motor 40 is light, the rotational speed of the bit rotation motor 40 will increase further.

[0151] 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, which accelerates the drilling of holes in the steel plate by the free rotation of the screw 200.

[0152] While the control unit 100 is performing a second load control operation, which involves limiting the rotation speed of the bit moving motor 50 and continuing the rotation of the bit rotating motor 40, it performs a drilling control operation to drill holes in the steel plate 203.

[0153] During the drilling section E1 in which drilling control is performed while the second load control is being executed, the control unit 100 detects the rotational speed of the bit movement motor 50 at a predetermined sampling interval, and at timing T3, which determines whether or not to relax the current limit as shown in Figure 13, it determines whether the rotational speed of the bit movement motor 50 is equal to or greater than the specified value for releasing the second load control.

[0154] If the control unit 100 determines in step SC10 that the rotational speed of the bit movement motor 50 has not reached the specified value for releasing the second load control, in step SC11, it increases the current supplied to the bit movement motor 50 from the current value limited by the second load control. By increasing the current supplied to the bit movement motor 50, the output of the bit movement motor 50, in this case its rotational speed, is increased, gradually increasing the amount of movement (advance movement) of the driver bit 2 along the axial direction.

[0155] This gradually increases the force with which the screw 200 is pressed against the object to be fastened via the driver bit 2, while suppressing the increase in the reaction force of the force with which the driver bit 2 presses against the object to be fastened via the screw 200, making it easier to drill a hole in the steel plate 203.

[0156] In step SC10, the control unit 100 determines that the rotational speed of the bit movement motor 50 is equal to or greater than the specified value for releasing the second load control. In step SC12, it switches from the second load control to the first load control and releases the current limit to the bit movement motor 50 at timing T4, as shown in Figure 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.

[0157] In other words, when the screw 200 drills a hole in the steel plate 203, the screw 200 is able to move (advance) in the axial direction, and the load on the driver bit 2 when it moves (advances) in the axial direction decreases. As a result, the amount of axial movement of the driver bit 2 can follow the amount of axial movement of the screw 200 when the screw 200 rotates and is tightened into the steel plate 203, and the rotational speed of the bit movement motor 50 increases. Therefore, by releasing the limit on the current flowing to the bit movement motor 50, in the screw tightening section E2, the driver bit 2 can be made to follow the screw 200 as it is tightened into the object to be fastened 202 and the steel plate 203, and the screw 200 can be tightened into the object to be fastened 202 and the steel plate 203.

[0158] In step SC14, the control unit 100 determines that the rotation amount of the bit movement 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 by the specified amount as shown in Figure 13, the control unit 100 stops driving the bit rotation motor 40 in step SC15, stops the rotation of the bit movement motor 50 in the forward direction in step SC16, and then reverses the bit movement motor 50 in step SC17.

[0159] In step SC18, when the holding member 30 and the moving member 32 have moved backward to the 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 SC19.

[0160] The control unit 100, after the load generation timing T1, determines that as the rotation speed V2 of the bit movement motor 50 decreases, the rotation speed V2 of the bit movement motor 50 does not fall below the high-load deceleration threshold S, and that the amount of decrease in the rotation speed of the bit movement motor 50 is within the range of normal deceleration, and determines that the screw 200 is being fastened to a normal fastening target object 202 such as wood or plaster, and continues the first load control. [Explanation of symbols]

[0161] 1... Fastening tool, 10... Tool body, 11... Handle, 2... Driver bit, 3... Bit holder, 30... Holding member, 31... Rotation guide member, 32... Moving member, 33... Biasing member, 4... First drive unit, 40... Bit rotation motor (first motor), 5... Second drive unit, 50... Bit movement motor (motor, second motor), 52... Pulley, 54... Wire, 6... Screw storage unit, 7... Screw feed unit, 8... Nose unit, 81... Contact member, 84... Contact switch unit, 9... Trigger, 90... Trigger switch unit, 100... Control unit (motor state detection unit, first motor state detection unit), 110... Setting unit (mode switching unit), 112... Load detection unit

Claims

1. A bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, A motor for moving the bit holding part in the axial direction, A control unit that controls the output of the motor to control the movement speed of the bit holder, A motor state detection unit for detecting the rotational speed of the motor, The contact member that is pressed against the object to be fastened and Equipped with, When the contact member is pressed against the object to be fastened, the motor moves the bit holder in the axial direction, causing the driver bit to advance in the axial direction and drill a hole in the object to be fastened with a screw engaged with the driver bit. The control unit controls the movement speed of the bit holder based on the change in the rotational speed of the motor due to the change in the load applied to the driver bit in the axial direction. When fastening the screw engaged with the driver bit to the object to be fastened, if the movement speed of the bit holder, determined from the rotational speed of the motor, falls below the movement speed of the bit holder corresponding to the decrease in the rotational speed of the motor as the load applied to the driver bit in the axial direction increases, the control unit reduces the output of the motor to follow the decrease in the amount of movement of the driver bit due to the increase in the load applied to the object to be fastened by pressing the screw against it and drilling a hole. Fastening tools.

2. The control unit, after reducing the output of the motor, increases the movement speed of the bit holder to a range less than the movement speed of the bit holder before reducing the output of the motor when predetermined conditions for increasing the movement speed of the bit holder are met. The fastening tool according to claim 1.

3. After reducing the output of the motor, the control unit satisfies predetermined conditions for increasing the movement speed of the bit holder, and when it determines that the movement speed of the bit holder has increased, it restores the movement speed of the bit holder to the speed it was at before the movement speed of the bit holder was reduced. The fastening tool according to claim 1.

4. A bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, A motor for moving the bit holding part in the axial direction, A control unit that controls the output of the motor to control the movement speed of the bit holder, A motor state detection unit for detecting the rotational speed of the motor, A mode switching unit that can switch between a first control mode that performs control to reduce the output of the motor regardless of the magnitude of the load applied in the axial direction of the driver bit, and a second control mode that performs control to reduce the output of the motor according to the magnitude of the load applied in the axial direction of the driver bit, The contact member that is pressed against the object to be fastened and Equipped with, When the contact member is pressed against the object to be fastened, the control unit controls the movement speed of the bit holder based on the change in the rotational speed of the motor due to the change in the load applied to the driver bit, when the motor moves the bit holder in the axial direction and the driver bit advances in the axial direction to drill a hole in the object to be fastened with the screw engaged with the driver bit, and when the control mode is the first control mode, when the motor determines that the movement speed of the bit holder has decreased when fastening the screw engaged with the driver bit to the object to be fastened, the control unit presses the screw against the object to be fastened. As the load for drilling increases, the motor output is reduced to follow the decrease in the amount of movement of the driver bit. When the control mode is in the second control mode, if it is determined that the movement speed of the bit holder, which is determined from the rotational speed of the motor, falls below the movement speed of the bit holder, which decreases with increasing axial load on the driver bit, the motor output is reduced to follow the decrease in the amount of movement of the driver bit as the load for drilling increases. Fastening tools.

5. The control unit, after reducing the output of the motor, increases the movement speed of the bit holder to a range less than the movement speed of the bit holder before reducing the output of the motor when predetermined conditions for increasing the movement speed of the bit holder are met. The fastening tool according to claim 4.

6. After reducing the output of the motor, the control unit satisfies predetermined conditions for increasing the movement speed of the bit holder, and when it determines that the movement speed of the bit holder has increased, it restores the movement speed of the bit holder to the speed it was at before the movement speed of the bit holder was reduced. The fastening tool according to claim 4.

7. A bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, A motor for moving the bit holding part in the axial direction, A control unit that controls the output of the motor to control the movement speed of the bit holder, A motor state detection unit for detecting the rotational speed of the motor, The contact member that is pressed against the object to be fastened and Equipped with, When the contact member is pressed against the object to be fastened, the motor moves the bit holder in the axial direction, causing the driver bit to advance in the axial direction and drill a hole in the object to be fastened with a screw engaged with the driver bit. At the same time, the movement speed of the bit holder is controlled based on the change in the rotational speed of the motor due to the change in the load applied to the driver bit in the axial direction. Furthermore, when fastening the screw engaged with the driver bit to the object to be fastened, if the difference between the actual movement amount of the bit holder, determined from the rotational speed of the motor, and the target movement amount exceeds a threshold corresponding to the decrease in the rotational speed of the motor due to the increase in the load applied to the driver bit in the axial direction, the output of the motor is reduced to follow the decrease in the movement amount of the driver bit due to the increase in the load applied to the object to be fastened by pressing the screw against it and drilling a hole. Fastening tools.

8. A bit holder that holds a screwdriver bit that can engage with a screw, and is rotatable in the circumferential direction and movable in the axial direction of the screwdriver bit, A motor for moving the bit holding part in the axial direction, A control unit that controls the output of the motor to control the movement speed of the bit holder, A motor state detection unit for detecting the rotational speed of the motor, The contact member that is pressed against the object to be fastened and Equipped with, When the contact member is pressed against the object to be fastened, the motor moves the bit holder in the axial direction, causing the driver bit to advance in the axial direction and drill a hole in the object to be fastened with a screw engaged with the driver bit. At the same time, the movement speed of the bit holder is controlled based on the change in the rotational speed of the motor due to the change in the load applied to the driver bit in the axial direction. Furthermore, when fastening the screw engaged with the driver bit to the object to be fastened, if the cumulative difference between the actual movement of the bit holder, determined from the rotational speed of the motor, and the target movement exceeds a threshold corresponding to the decrease in the rotational speed of the motor due to the increase in the load applied to the driver bit in the axial direction, the output of the motor is reduced to follow the decrease in the movement of the driver bit due to the increase in the load applied to the object to be fastened by pressing the screw against it and drilling a hole. Fastening tools.

Images