Screw driving machine

Abstract

To provide a screw driving machine structured with a contact arm divided into two and capable of suppressing the increase of a load in an operation for moving the contact arm.SOLUTION: A screw driving machine 1A comprises: a lower arm 80 that is supported so as to be movable with respect to a body 10 and that comes into contact with a driven material; an upper arm 81 that is supported so as to be movable with respect to the body 10 and that operates a start valve 6; a transmission member 82 that transmits motion of the lower arm 80 to the upper arm 81; a guide groove 46a that guides movement of the transmission member 82 and switches the presence of interlocking between the lower and upper arms 80 and 81; a biasing member 84a that biases the transmission member 82; and a biasing force transmission member 84b that switches the presence of biasing of the transmission member 82 by the biasing member 84a in accordance with the position of the transmission member 82 guided by the guide groove 46a.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present disclosure relates to a screw driving machine that drives a screw into a workpiece and then tightens the screw. [Background technology]

[0002] A screw driver is a tool that uses compressed air as its power source, moves a driver bit axially to drive a screw into the material to the extent that the head of the screw floats above the material being driven, and then rotates the driver bit to tighten the screw into the material being driven.

[0003] With this type of screw driver, when driving a screw, the tip of the screw needs to penetrate the top material of the workpiece and be driven partway into the bottom material. However, if the screw is driven in too far, a hole larger than the screw diameter will be created in the bottom material, which can result in a short screw engagement and weak fastening force.

[0004] Therefore, a mechanism has been proposed in which a sliding member, such as a contact arm, that slides along the axis of the ejection part is provided at the tip of the ejection part that guides the driver bit and screw, and the tip of the sliding member is constantly biased to protrude, and an engaging means is provided that engages with the sliding member when the screw is driven in and disengages when the screw is tightened, thereby reducing the depth to which the screw is driven in and allowing the screw head to be tightened to a position where it is flush with the upper material of the material being driven in (see, for example, Patent Document 1).

[0005] However, in a two-stage stroke configuration in which the slide member is engaged with the engaging means when the screw is driven in, stopping the movement of the slide member midway, and then the engagement by the engaging means is released when the screw is tightened, allowing the slide member to move further, the amount of movement of the slide member becomes longer, and therefore the overall length of the device becomes longer.

[0006] Therefore, a mechanism has been proposed in which the slide member is divided into an upper arm portion and a lower arm portion, thereby reducing the amount of movement of the slide member (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3570485 [Patent Document 2] Patent No. 3632296 Summary of the Invention [Problem to be solved by the invention]

[0008] In order to be able to switch between whether or not the lower arm section and the upper arm section are linked together, a mechanism has been proposed in which the movement of the lower arm section can be transmitted to the upper arm section via a roller, and by guiding the direction of movement of the roller, it is possible to switch between a state in which the lower arm section and the upper arm section move in linkage with each other, and a state in which the linkage is released and the lower arm section moves independently of the upper arm section.

[0009] In such a configuration, the roller is biased by a biasing member so that the roller can move in a predetermined direction.

[0010] However, the biasing force that biases the roller acts on the lower arm portion and the upper arm portion via the roller, which increases the load in the operation of moving the lower arm portion and the upper arm portion.

[0011] The present disclosure has been made to solve such problems, and aims to provide a screw driver that has a contact tact arm divided into two parts, making it possible to suppress an increase in load when moving the contact arm. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the present invention provides a driving section to which compressed air is supplied and which moves a driver bit in the axial direction, a tightening section to which compressed air is supplied and which rotates the driver bit around its axis, a main valve which switches on and off the supply of compressed air to the driving section and the tightening section, a starting valve which operates the main valve, a first arm which is supported so as to be movable along the axial direction of the driver bit and which comes into contact with the material to be driven, a second arm which is supported so as to be movable along the axial direction of the driver bit and which operates the starting valve, and a valve which moves to a position where the movement of the first arm can be transmitted to the second arm and which starts the first arm. a transmission member that links the first arm and the second arm and that can move to a position where the movement of the first arm is not transmitted to the second arm, thereby disengaging the linkage between the first arm and the second arm; a guide section that guides the movement of the transmission member and switches between interlocking the first arm and the second arm and non-interlocking depending on the position of the guiding transmission member; a biasing member that biases the transmission member toward a position where the movement of the first arm can be transmitted to the second arm; and a biasing force switching section that regulates the biasing force of the biasing member on the transmission member and switches the strength of the biasing force of the biasing member depending on the position of the transmission member guided by the guide section.

[0013] In the present disclosure, a first arm is pressed against a workpiece to be driven, and a transmission member moves in conjunction with the movement of the first arm. The transmission member moves while being guided by a guide portion. The movement of the transmission member while being guided by the guide portion switches between interlocking the first arm and the second arm and whether or not they are interlocked.

[0014] The first and second arms move in tandem, and when the second arm activates the start valve, the main valve is activated, supplying compressed air to the driving section, causing the driver bit to move axially and driving the screw into the workpiece. Compressed air is also supplied to the tightening section, causing the driver bit to rotate around its axis and tightening the screw that has been driven into the workpiece.

[0015] Furthermore, when the interlocking of the first arm and the second arm is released, the first arm becomes movable in conjunction with the tightening of the screw, but the second arm is not interlocked with the first arm and does not move.

[0016] The biasing member biases the transmission member in a direction that moves the transmission member to a position where the movement of the first arm can be transmitted to the second arm. The strength of the biasing force exerted by the biasing member on the transmission member is switched depending on the position of the transmission member guided by the guide section. When the first arm is pressed against the workpiece and the first and second arms move in unison, the biasing force exerted by the biasing member on the transmission member is weakened relative to when the first and second arms are released from unison and the first arm moves. [Effects of the Invention]

[0017] In the present disclosure, when the first arm is pressed against the workpiece, the load generated by the biasing member biasing the transmission member can be suppressed. Also, when the transmission member is moved to a position where the movement of the first arm can be transmitted to the second arm, the biasing member can reliably move the transmission member. [Brief explanation of the drawings]

[0018] [Figure 1A] 1 is a side cross-sectional view showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 1B] 1 is a front cross-sectional view showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 1C] 1 is a side view showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 1D] 1 is a side view showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 2A] 1 is a side cross-sectional view of a main part showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 2B] 1 is a perspective view of a main part showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 2C] 1 is a perspective view of a main part showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 2D] 1 is a perspective view of a main part showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 2E] FIG. 4 is a cross-sectional view showing an example of a transmission member. [Figure 2F] FIG. 4 is a cross-sectional view showing an example of a transmission member. [Figure 3A] FIG. 10 is a side view showing an example of a lower arm. [Figure 3B] FIG. 10 is a side view showing an example of an upper arm. [Figure 3C] FIG. 10 is a side view illustrating an example of a switching member. [Figure 3D] FIG. 4 is a side view illustrating an example of a biasing force transmission member. [Figure 4A] 1 is a side cross-sectional view of a main part of a screw driving machine according to an embodiment of the present invention, showing an example of the operation of driving a screw into a workpiece and tightening it. FIG. [Figure 4B] 1 is a side cross-sectional view of a main part of a screw driving machine according to an embodiment of the present invention, showing an example of the operation of driving a screw into a workpiece and tightening it. FIG. [Figure 5A] 1 is a side cross-sectional view of a main part showing an example of a screw driver according to an embodiment of the present invention, which is equipped with a screw driving depth switching unit. [Figure 5B] 1 is a side cross-sectional view of a main part showing an example of a screw driver according to an embodiment of the present invention, which is equipped with a screw driving depth switching unit. [Figure 5C] 1 is a side view showing an example of a screw driver according to an embodiment of the present invention, which is equipped with a screw driving depth switching unit. [Figure 5D] 1 is a bottom cross-sectional view of a main part showing an example of a screw driver according to the present embodiment, which is equipped with a screw driving depth switching unit. FIG. [Figure 5E] 1 is a bottom cross-sectional view of a main part showing an example of a screw driver according to the present embodiment, which is equipped with a screw driving depth switching unit. FIG. [Figure 6] 1 is a perspective view of a main part showing an example of a screw driving machine according to an embodiment of the present invention, which is equipped with a screw driving depth switching unit. FIG. [Figure 7A] FIG. 10 is a side view showing an example of a lower arm of a screw driver equipped with a driving depth switching unit. [Figure 7B]FIG. 10 is a side view showing an example of a switching member of a screw driver equipped with a driving depth switching unit. [Figure 8A] 1 is a side cross-sectional view of the main part of the screw driver of the present embodiment, showing an example of the operation of driving a screw into a workpiece and tightening it when the first mode is selected. FIG. [Figure 8B] 1 is a side cross-sectional view of the main part of the screw driver of the present embodiment, showing an example of the operation of driving a screw into a workpiece and tightening it when the first mode is selected. FIG. [Figure 9] 10 is a cross-sectional side view of the main part of the screw driver of the present embodiment, showing an example of the operation of driving a screw into a workpiece and tightening it when the second mode is selected. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of a screw driver according to the present invention will be described with reference to the drawings.

[0020] <Configuration example of the screw driving machine according to this embodiment> Fig. 1A is a side cross-sectional view showing an example of a screw driving machine according to the present embodiment, Fig. 1B is a front cross-sectional view showing an example of the screw driving machine according to the present embodiment, Fig. 1C and Fig. 1D are side views showing an example of the screw driving machine according to the present embodiment, Fig. 2A is a side cross-sectional view of a main part of an example of the screw driving machine according to the present embodiment, and Fig. 2B, Fig. 2C, and Fig. 2D are perspective views of a main part of an example of the screw driving machine according to the present embodiment.

[0021] The screw driver 1A uses the air pressure of compressed air to move the driver bit 2 in the axial direction. The screw driver 1A also uses the air pressure of compressed air to rotate the driver bit 2 about its axis. By moving the driver bit 2 in the axial direction, the screw driver 1A drives the screw 200 into the workpiece 300 to such an extent that the head of the screw 200 floats above the workpiece 300. The screw driver 1A also rotates the driver bit 2 about its axis to tighten the screw 200 that has been driven into the workpiece 300.

[0022] The screw driver 1A is designed to be held by hand and includes a main body 10 and a handle 11. The main body 10 extends along the axial direction of the driver bit 2.

[0023] The screw driver 1A has a handle portion 11 provided near the middle of the extension direction of the main body portion 10. The handle portion 11 extends in a direction intersecting with the main body portion 10. The screw driver 1A also has a nose portion 12 provided on one side of the main body portion 10 in the extension direction.

[0024] As shown in Figure 1A and other figures, the screw driver 1A is illustrated with the nose portion 12 facing downward, and one side along the extension direction of the main body portion 10 is referred to as the lower side, and the other side along the extension direction of the main body portion 10 is referred to as the upper side. In the screw driver 1A, the downward direction is indicated by arrow D. Furthermore, in the screw driver 1A, the upward direction, which is opposite to the downward direction, is indicated by arrow U. The axial direction of the driver bit 2 is oriented along the vertical direction, and it moves downward and upward.

[0025] The nose portion 12 includes an injection passage 12a through which the screw 200 is supplied, an injection port 12b through which the screw 200 supplied to the injection passage 12a is injected, and a closing portion 12c that closes the bottom end of the main body portion 10. In the screw driving machine 1A, the main body portion 10 and the nose portion 12 are separate components. The main body portion 10 has an open bottom end, and an opening 10a is formed at the bottom end. The opening 10a has a shape that allows the driver bit 2 to pass through. The closing portion 12c of the nose portion 12 is attached to the bottom end of the main body portion 10. The closing portion 12c is shaped to allow the driver bit 2 to pass through and closes the opening 10a.

[0026] The injection passage 12a extends in the vertical direction in which the driver bit 2 moves. The injection port 12b is formed by providing an opening at the lower end of the injection passage 12a in the extension direction. The closing portion 12c has an introduction portion 12d through which the driver bit 2 passes. The introduction portion 12d is formed by providing an opening at the upper end of the injection passage 12a in the extension direction. The closing portion 12c is formed on the outer periphery of the introduction portion 12d.

[0027] The screw driver 1A includes a striking cylinder 30 that moves the driver bit 2 in the axial direction, and a striking piston 30a that moves by the air pressure of compressed air supplied to the striking cylinder 30.

[0028] The screw driver 1A also includes an air motor 31 that rotates the driver bit 2 around its axis, and a motor shaft 31a that rotates by the air pressure of compressed air supplied to the air motor 31.

[0029] The striking cylinder 30 is an example of a driving section, and is provided inside the main body 10 and is configured as a cylindrical space extending in the vertical direction.

[0030] A striking piston 30a is provided inside the striking cylinder 30. The striking piston 30a is formed in a disk shape, a cylindrical shape, or the like, and is capable of moving inside the striking cylinder 30 in the vertical direction.

[0031] The striking piston 30a is attached with the motor shaft 31a protruding upward, and the striking piston 30a is detachably attached via the motor shaft 31a with the driver bit 2 protruding downward.

[0032] In the screw driving machine 1A, the striking piston 30a moves up and down inside the striking cylinder 30, causing the driver bit 2 and the motor shaft 31a to move in the directions of arrows D and U along the axial direction of the driver bit 2. In addition, in the screw driving machine 1A, the motor shaft 31a rotates, causing the driver bit 2 to rotate around its own axis.

[0033] As a result, in the screw driver 1A, the air pressure of the compressed air supplied to the striking cylinder 30 causes the striking piston 30a to move the driver bit 2 axially downward as indicated by the arrow D, thereby driving the screw 200 into the workpiece. Also, in the screw driver 1A, the air pressure of the compressed air supplied to the air motor 31 causes the motor shaft 31a to rotate the driver bit 2 about its axis, thereby tightening the screw 200 into the workpiece.

[0034] The striking piston 30a has a first seal portion 30b1 and a second seal portion 30b2 attached to its outer periphery. The first seal portion 30b1 and the second seal portion 30b2 are provided at two locations along the direction of movement of the striking piston 30a, with a predetermined distance between them. The first seal portion 30b1 is provided on the lower side along the direction of movement of the striking piston 30a, and the second seal portion 30b2 is provided on the upper side along the direction of movement of the striking piston 30a. The first seal portion 30b1 and the second seal portion 30b2 protrude from the outer periphery of the striking piston 30a and contact the inner circumferential surface of the striking cylinder 30. Furthermore, the first seal portion 30b1 and the second seal portion 30b2 slide against the inner circumferential surface of the striking cylinder 30 as the striking piston 30a moves up and down.

[0035] As a result, the interior of the striking cylinder 30 is partitioned by the striking piston 30a, and airtightness between the space above and below the striking piston 30a is maintained by the first seal portion 30b1 and the second seal portion 30b2.

[0036] The striking cylinder 30 has a first chamber 30c formed below the striking piston 30a and a second chamber 30d formed above the striking piston 30b. The first chamber 30c is an example of a striking cylinder lower chamber and is formed as the space below the striking piston 30a. The second chamber 30d is an example of a striking cylinder upper chamber and is formed as the space above the striking piston 30a.

[0037] The lower end of the first chamber 30c of the striking cylinder 30 is closed by the closing portion 12c of the nose portion 12. The striking cylinder 30 also has a bumper 30e at the lower end of the first chamber 30c. The bumper 30e is made of an elastic material and is attached to the closing portion 12c. The bumper 30e is annular and has a shape that allows the striking piston 30a to contact it. The central opening of the bumper 30e is connected to the lead-in portion 12d of the closing portion 12c, allowing the driver bit 2 to pass through the central opening. The striking piston 30a can move downward to a position where it contacts the bumper 30e. The striking piston 30a and the driver bit 2 are at their bottom dead center positions when the striking piston 30a contacts the bumper 30e. The bumper 30e is elastically deformable, and the bottom dead center positions of the striking piston 30a and the driver bit 2 can move within the range of elastic deformation of the bumper 30e.

[0038] The screw driver 1A also includes a wall 30f between the striking cylinder 30 and the air motor 31, which closes the upper end of the second chamber 30d. The striking cylinder 30 also includes a bumper 30g at the upper end of the second chamber 30d. The bumper 30g is made of an elastic material and is attached to the wall 30f. The bumper 30g is annular and has a shape that allows the striking piston 30a to contact it. The motor shaft 31a can pass through the opening in the center of the bumper 30g. The striking piston 30a can move upward to a position where it contacts the bumper 30g. The striking piston 30a and the driver bit 2 are at their top dead center positions when the striking piston 30a contacts the bumper 30g. The bumper 30g is elastically deformable, and the top dead center positions of the striking piston 30a and the driver bit 2 can move within the range of elastic deformation of the bumper 30g.

[0039] The air motor 31 is an example of a fastening unit and includes a rotor 31b1 that rotates when compressed air is supplied to it, blades 31b2 that receive the airflow that rotates the rotor 31b1, and a motor housing 31c that rotatably supports the rotor 31b1 and generates the airflow that rotates the rotor 31b1. The air motor 31 has a motor shaft 31a inserted into a hole 31b3 formed in the rotor 31b1. The rotation of the rotor 31b1 is transmitted to the motor shaft 31a via a reducer 31d. The reducer 31d is, for example, a planetary gear mechanism and is located between the impact cylinder 30 and the air motor 31.

[0040] The motor shaft 31a is supported by the reducer 31d so as to be movable in the axial direction, thereby allowing the motor shaft 31a to move vertically together with the striking piston 30a and the driver bit 2.

[0041] When the rotor 31b1 of the air motor 31 rotates, the motor shaft 31a rotates at a predetermined reduction ratio via the reducer 31d.

[0042] The air motor 31 is provided above the striking cylinder 30. The motor shaft 31a is provided coaxially with the driver bit 2. As a result, the air motor 31 is provided above the main body 10, coaxially with the striking cylinder 30. The air motor 31 is configured so that the motor shaft 31a is inserted into a hole 31b3 provided in the rotor 31b1, ensuring space for the motor shaft 31a to move up and down.

[0043] The screw driving machine 1A includes a main valve 5 that switches between supplying and not supplying compressed air to the striking cylinder 30 and the air motor 31, a start valve 6 that operates the main valve 5, and a trigger 60 that operates the start valve 6. The screw driving machine 1A also includes an on-off valve 7 that switches between supplying and not supplying compressed air to the air motor 31, and a control unit 70 that operates the on-off valve 7.

[0044] Furthermore, the screw driver 1A is provided with a contact arm 8 that is movably mounted relative to the main body 10, and that can operate the start valve 6 in cooperation with the operation of the trigger 60, and that also operates the control unit 70. The screw driver 1A is also provided with a driving depth restriction unit 4a that restricts and releases the relative movement of the contact arm 8 with respect to the main body 10 by the operation of moving the contact arm 8 and the main body 10 relative to each other, and that restricts the driving depth of the screw 200 into the workpiece 300.

[0045] Furthermore, the screw driver 1A includes a screw feed unit 9 that feeds the screws 200 to the nose unit 12 and a magazine 90 that stores the screws 200 fed by the screw feed unit 9.

[0046] The screw driver 1A also has a main chamber 13 to which compressed air is supplied from an external air compressor (not shown). The main chamber 13 is provided on the outer periphery of the striking cylinder 30 within the handle portion 11 and the body portion 10 connected to the handle portion 11, and is supplied with compressed air that has been decompressed by a pressure reducing valve 13a. The screw driver 1A also has an exhaust pipe 14 that exhausts compressed air supplied to the striking cylinder 30, air motor 31, etc. The exhaust pipe 14 is provided in the handle portion 11 and exhausts the compressed air through an exhaust filter 14a.

[0047] The screw driver 1A also includes a timer chamber 32 to which compressed air is supplied to operate the control unit 70, and a blowback chamber 33 to which compressed air is supplied to return the striking piston 30a, which has moved to the bottom dead center position, to the top dead center position and to operate the screw feed unit 9.

[0048] The timer chamber 32 and blowback chamber 33 are provided inside the main body 10 on the outer periphery of the striking cylinder 30. The timer chamber 32 is in communication with the space inside the striking cylinder 30 via a side hole flow passage 32a provided on the side of the striking cylinder 30. The side hole flow passage 32a is provided below the center, between the upper and lower ends of the striking cylinder 30.

[0049] The timer chamber 32 is connected to a first chamber 30c formed below the striking piston 30a via the side hole flow passage 32a while the striking piston 30a moves from the top dead center position to a position where the first seal portion 30b1 passes through the side hole flow passage 32a, and is blocked from a second chamber 30d formed above the striking piston 30a by the second seal portion 30b2. When the striking piston 30a moves until the side hole flow passage 32a is positioned between the first seal portion 30b1 and the second seal portion 30b2, the timer chamber 32 is blocked from the first chamber 30c and the side hole flow passage 32a by the first seal portion 30b1, and the second chamber 30d and the side hole flow passage 32a are blocked by the second seal portion 30b2. When the striking piston 30a moves to the bottom dead center position, the timer chamber 32 is connected to the second chamber 30d via the side hole flow passage 32a.

[0050] The blowback chamber 33 is connected to the space inside the striking cylinder 30 via side hole flow passages 33a and 33b provided on the side of the striking cylinder 30. The side hole flow passage 33a is provided above the bumper 30e and near the lower end of the striking cylinder 30. The side hole flow passage 33b is provided between the lower and upper ends of the striking cylinder 30, above the center.

[0051] The blowback chamber 33 is connected to the first chamber 30c via the side hole flow passage 33a. When the striking piston 30a moves downward from the top dead center position to a position where it passes through the side hole flow passage 33b, the blowback chamber 33 is connected to the second chamber 30d via the side hole flow passage 33b.

[0052] The main valve 5 is provided on the outer periphery of the striking cylinder 30 so as to be movable up and down. In the screw driving machine 1A, an upper main valve chamber 52 is provided above the main valve 5, and the upper main valve chamber 52 is connected to the starting valve 6.

[0053] The screw driving machine 1A also has a main valve lower chamber 53 below the main valve 5, which is connected to the main chamber 13. The screw driving machine 1A also has an air flow path 54 between the striking cylinder 30 and the main valve 5. The screw driving machine 1A also has a supply port 34 on the side surface of the upper end of the striking cylinder 30. The screw driving machine 1A also has an air flow path 54 connected to the striking cylinder 30 via the supply port 34. The screw driving machine 1A also has an air flow path 74 between the air flow path 54 and the air motor 31, which connects the air flow path 54 to the air motor 31 via the air flow path 74.

[0054] In the screw driving machine 1A, when the main valve 5 moves downward, the air flow path 54 is blocked from the main valve lower chamber 53 by the main valve 5. In the screw driving machine 1A, when the main valve 5 moves to a position where it blocks the air flow path 54 from the main valve lower chamber 53, the air flow path 54 is connected to the exhaust pipe 14. In addition, in the screw driving machine 1A, when the main valve 5 moves upward, the air flow path 54 is connected to the main valve lower chamber 53 via the main valve 5.

[0055] The main valve 5 is biased downward by a main valve spring 51, which is a direction that closes the air flow path 54. The main valve spring 51 is provided in an upper chamber 52 of the main valve.

[0056] Compressed air is supplied from the main chamber 13 to the main valve upper chamber 52 via the starting valve 6, and the main valve 5 is pushed downward by the air pressure of the compressed air. Compressed air is also supplied from the main chamber 13 to the main valve lower chamber 53 of the main valve 5, and the main valve 5 is pushed upward by the air pressure of the compressed air.

[0057] As a result, the main valve 5 opens and closes the air flow path 54 connecting the main chamber 13 with the striking cylinder 30 and the air motor 31. When not in operation, the main valve 5 is biased downward to its bottom dead center position due to the balance of the air pressures of the compressed air supplied to the main valve upper chamber 52 and the main valve lower chamber 53, and the force of the main valve spring 51, blocking the air flow path 54 between the main valve lower chamber 53 and the striking cylinder 30. When in operation, on the other hand, the main valve upper chamber 52 communicates with the atmosphere via the starting valve 6, so that the main valve 5 is pushed upward by the air pressure of the compressed air supplied from the main chamber 13 to the main valve lower chamber 53, opening the air flow path 54 between the main valve lower chamber 53 and the striking cylinder 30.

[0058] The starting valve 6 includes a pilot valve 61 that opens and closes the main valve upper chamber 52, a valve stem 62 that operates the pilot valve 61, and a valve stem spring 63 that urges the pilot valve 61 upward and urges the valve stem 62 downward.

[0059] In the starting valve 6, the pilot valve 61 is pushed downward by the air pressure of the compressed air supplied from the main chamber 13. In addition, in the starting valve 6, the pilot valve 61 is pushed upward by the air pressure of the compressed air supplied from the main chamber 13 to the valve lower chamber 64.

[0060] As a result, the pilot valve 61 of the starting valve 6 is held in the upper position due to the balance of the compressed air pressure and the force of the valve stem spring 63. In contrast, when the valve stem 62 of the starting valve 6 moves upward, the valve lower chamber 64 communicates with the atmosphere, causing the pilot valve 61 to move downward due to the compressed air pressure. Then, as the pilot valve 61 moves downward, a passage that connects the main valve upper chamber 52 with the atmosphere opens.

[0061] The trigger 60 is provided below the handle portion 11, and rotates around 60c as a fulcrum when operated by an operator. The trigger 60 is biased in a direction away from the valve stem 62 of the starting valve 6 by a trigger spring 60d.

[0062] The trigger 60 includes a contact lever 60a that operates a valve stem 62 of the starting valve 6. The contact lever 60a is supported by the trigger 60 so as to be rotatable about a shaft 60b.

[0063] In the starting valve 6, when the contact arm 8 is pressed against the workpiece 300, the contact arm 8 moves upward relative to the main body 10, and the trigger 60 is pulled, which combines this movement, causing the contact lever 60a to come into contact with the valve stem 62 and the valve stem 62 to move upward. The starting valve 6 is activated when the valve stem 62 moves upward.

[0064] In contrast, in the starting valve 6, the contact arm 8 is pressed against the workpiece 300, causing the contact arm 8 to move upward relative to the main body 10, or the trigger 60 is pulled, so that the contact lever 60a does not come into contact with the valve stem 62.

[0065] As a result, the starting valve 6 is actuated by a combination of the operation of the trigger 60 and the operation of pressing the contact arm 8. The order in which the operation of the trigger 60 and the operation of pressing the contact arm 8 are performed is arbitrary.

[0066] The on-off valve 7 is supported by an on-off valve cylinder 73 provided on the side of the main body 10 so as to be movable up and down. The on-off valve cylinder 73 is provided with an on-off valve lower chamber 73a below the on-off valve 7. An upper on-off valve chamber 73b is provided above the on-off valve 7. When compressed air is supplied to the upper on-off valve chamber 73b, the on-off valve 7 moves downward due to the pressure of the compressed air. When compressed air is not supplied to the upper on-off valve chamber 73b, the on-off valve 7 moves upward due to the pressure of the compressed air supplied to the lower on-off valve chamber 73a.

[0067] The on-off valve 7 moves downward to close the air flow path 74, blocking the flow of air between the main chamber 13 and the air motor 31. The on-off valve 7 moves upward to open the air flow path 74, allowing electrical communication between the main chamber 13 and the air motor 31.

[0068] The control unit 70 includes a control valve cylinder 75 and a first control valve 72 housed in the control valve cylinder 75. The first control valve 72 is supported by the control valve cylinder 75 so as to be able to move up and down, and divides the interior of the control valve cylinder 75 into a third chamber 75a and a fourth chamber 75b. The control unit 70 also includes a communication passage 75c that connects the third chamber 75a to the timer chamber 32. The communication passage 75c connects the striking cylinder 30 to the third chamber 75a via the timer chamber 32. The control unit 70 also includes a second control valve 71 that is provided above the first control valve 72.

[0069] The control unit 70 also includes a first biasing member 72b that biases the first control valve 72 downward, and a second biasing member 71a that biases the second control valve 71 downward.

[0070] The third chamber 75a of the control valve cylinder 75 communicates with the space inside the striking cylinder 30 via the timer chamber 32. The third chamber 75a of the control valve cylinder 75 also communicates with the outside of the body of the screw driving tool 1A via an exhaust passage 75d.

[0071] The first control valve 72 is biased downward by the first biasing member 72b, and moves downward. By moving downward, the first control valve 72 moves to the bottom dead center position. Furthermore, by moving upward from the bottom dead center position, the first control valve 72 moves to the top dead center position, passing through the pressure control start position.

[0072] The first control valve 72 includes a seal portion 72c that opens and closes the exhaust passage 75d. When the first control valve 72 is in a standby state at the standby position P100, the seal portion 72c is moved to a position that opens the exhaust passage 75d. When the seal portion 72c is moved to a position that opens the exhaust passage 75d, the third chamber 75a of the control valve cylinder 75 communicates with the outside of the machine body of the screw driving machine 1A via the exhaust passage 75d.

[0073] The second control valve 71 is formed of a rod-shaped member extending in the vertical direction, and is supported relative to the on-off valve 7 so as to be able to move up and down. The second control valve 71 is urged in the direction of arrow D by a second urging member 71a, thereby moving to a standby position P110. The second control valve 71 is also pressed by the first control valve 72 and is activated. The second control valve 71 moves from the standby position P110 to an activation end position, and switches between supplying and not supplying compressed air to the on-off valve upper chamber 73b of the on-off valve cylinder 73, thereby activating the on-off valve 7.

[0074] The screw feed unit 9 includes a feed member 91 that feeds the screw 200, and a feed piston 92 that operates the feed member 91. The feed member 91 is supported so as to be movable toward and away from the nose section 12, and feeds the screw 200, which is connected by a connecting band 201, to the injection passage 12a of the nose section 12 while engaging the screw 200 with a claw portion (not shown).

[0075] The feed piston 92 is connected to the feed member 91 and is slidably provided in a feed cylinder 93. The feed cylinder 93 is connected to the blowback chamber 33 via a feed flow path 94, and compressed air is supplied from the blowback chamber 33.

[0076] Feed piston 92 is actuated by the air pressure of compressed air supplied from blowback chamber 33, and moves feed member 91 in a direction away from nose portion 12. Furthermore, feed piston 92 is urged in the direction of arrow R by urging member 95 such as a coil spring, and when the air pressure inside feed cylinder 93 on the arrow R side relative to feed piston 92 decreases, the urging of urging member 95 moves feed member 91 in a direction toward nose portion 12.

[0077] The magazine 90 is provided below the handle portion 11 and connected to the nose portion 12. The magazine 90 stores a screw connecting body in which a plurality of screws 200 are connected by connecting bands 201 and which is wound, for example, in a spiral shape.

[0078] The contact arm 8 is an example of a contact portion, and includes a lower arm 80 that comes into contact with the workpiece 300, and an upper arm 81 that presses the contact lever 60a of the trigger 60. The contact arm 8 also includes a transmission member 82 that transmits the movement of the lower arm 80 to the upper arm 81.

[0079] 2E and 2F are cross-sectional views showing an example of a transmission member. The transmission member 82 includes a first roller 82a, a second roller 82b, a third roller 82c, and a shaft 82d. The first roller 82a, the second roller 82b, and the third roller 82c are arranged coaxially with the shaft 82d and are arranged in parallel along the extension direction of the shaft 82d. The first roller 82a, the second roller 82b, and the third roller 82c are supported on the shaft 82d so as to be independently rotatable.

[0080] The first roller 82a has an expanded diameter portion 82a1 at the end opposite the second roller 82b. The expanded diameter portion 82a1 is circular and has a diameter larger than that of the first roller 82a. The third roller 82c has an expanded diameter portion 82c1 at the end opposite the second roller 82b. The expanded diameter portion 82c1 is circular and has a diameter larger than that of the third roller 82c.

[0081] The shaft 82d has an abutment portion 82e at its end facing the third roller 82c. The abutment portion 82e is circular and has a diameter larger than that of the shaft 82d. When the shaft 82d is inserted into the third roller 82c, the abutment portion 82e protrudes outward in the axial direction of the shaft 82d relative to the end of the third roller 82c. A retaining member (not shown) is detachably attached to the end of the shaft 82d facing the first roller 82a.

[0082] As a result, the first roller 82a, the second roller 82b, and the third roller 82c are prevented from coming off the shaft 82d by the abutted portion 82e and a retaining member (not shown). Furthermore, the transmission member 82 allows the first roller 82a, the second roller 82b, and the third roller 82c to move together in a direction intersecting the axial direction of the shaft 82d.

[0083] The lower arm 80 and the upper arm 81 are configured to be movable downward and upward relative to the main body 10. The lower arm 80 moves downward and upward to move the transmission member 82. The direction of movement of the transmission member 82 is guided by a switching member 46, which will be described later. Depending on the direction in which the transmission member 82 moves, the lower arm 80 and the upper arm 81 can be switched between a state in which the lower arm 80 and the upper arm 81 move in the vertical direction in conjunction with each other, and a state in which the conjunction is released and the lower arm 80 moves in the vertical direction independently of the upper arm 81.

[0084] The lower arm 80 is an example of a first arm, and is supported on the nose portion 12 of the screw driver 1A so as to be movable in the vertical direction, and is biased downward by a biasing member 83a formed of a coil spring or the like.

[0085] 3A is a side view showing an example of a lower arm 80. The lower arm 80 has a cam groove 88 that moves the transmission member 82.

[0086] The cam groove 88 includes a first cam groove 88a extending obliquely relative to the directions of the arrows U and D (up and down directions), and a second cam groove 88b extending along the directions of the arrows U and D.

[0087] The directions intersecting the directions of arrows U and D are indicated by arrows L and R. Arrows L and R also represent directions approaching and receding from the injection passage 12a of the nose portion 12, with arrow R representing the direction approaching the injection passage 12a and arrow L representing the direction receding from the injection passage 12a. The first cam groove 88a is inclined at a predetermined angle such that the upper side faces the arrow R side and the lower side faces the arrow L side.

[0088] The first cam groove 88a has a first engagement portion 88c formed by the lower side of a pair of opposing sides inclined in the same direction, and a second engagement portion 88d formed by the upper side.

[0089] In the first cam groove 88a, the first engagement portion 88c and the second engagement portion 88d face each other at a predetermined distance that allows the second roller 82b to fit between the first engagement portion 88c and the second engagement portion 88d. The second roller 82b is movable between the first engagement portion 88c and the second engagement portion 88d along the direction in which the first engagement portion 88c and the second engagement portion 88d extend. The first engagement portion 88c and the second engagement portion 88d may be configured as straight lines or curved lines.

[0090] The upper arm 81 is an example of a second arm, and is supported on the side of the main body 10 of the screw driver 1A so as to be movable in the vertical direction, and is biased downward by a biasing member 83b formed of a coil spring or the like.

[0091] 3B is a side view showing an example of an upper arm. Upper arm 81 includes guide groove 81a to which the movement of lower arm 80 is transmitted via transmission member 82, and pressing member 87 that presses contact lever 60a.

[0092] The guide groove 81a has an elongated hole shape extending in the directions of the arrows L and R. The guide groove 81a is configured so that the distance between two opposing sides in the short direction is slightly longer than the diameter of the third roller 82c. This allows the third roller 82c to fit into the guide groove 81a and guides the movement of the third roller 82c in the directions of the arrows L and R. The pressing member 87 is configured with a portion that protrudes upward. The pressing member 87 may be configured integrally with the upper arm 81, or may be configured as a separate component.

[0093] The screw driver 1A includes a switching member 46 that switches between interlocking the lower arm 80 and the upper arm 81 and interlocking the upper arm 81.

[0094] 3C is a side view showing an example of a switching member. Switching member 46 is an example of a guide portion, and is provided with guide groove 46a that guides transmission member 82 to move it to a predetermined position. Switching member 46 switches between interlocking and non-interlocking of lower arm 80 and upper arm 81 depending on the position of transmission member 82 guided by guide groove 46a.

[0095] The guide groove 46a includes a first guide groove 46a1 extending in the up-down direction. The first guide groove 46a1 is configured so that the distance between two opposing short sides is slightly longer than the diameter of the first roller 82a. As a result, the first guide groove 46a1 allows the first roller 82a to enter and guides the first roller 82a along the movement direction of the lower arm 80 while restricting movement of the first roller 82a in the directions of arrows L and R.

[0096] The guide groove 46a includes a second guide groove 46a2 extending in the directions of arrows L and R. The second guide groove 46a2 is configured so that the distance between two opposing sides in the short direction is slightly longer than the diameter of the first roller 82a. As a result, the second guide groove 46a2 allows the first roller 82a to enter and guides the first roller 82a in the directions of arrows L and R that intersect with the movement direction of the lower arm 80 while restricting the first roller 82a from moving along the movement direction of the lower arm 80.

[0097] The guide groove 46a includes a third guide groove 46a3 that guides the first roller 82a between the first guide groove 46a1 and the second guide groove 46a2. The third guide groove 46a3 has an inner side that is curved at the portion where it bends from the first guide groove 46a1 to the second guide groove 46a2, and an outer side that is curved and sloped.

[0098] In the screw driver 1A, the cam groove 88 of the lower arm 80, the guide groove 81a of the upper arm 81, and the guide groove 46a of the switching member 46 overlap with each other.

[0099] The first roller 82a, the second roller 82b, and the third roller 82c of the transmission member 82 are placed in a space formed at the intersection of the cam groove 88, the guide groove 81a, and the guide groove 46a. This supports the transmission member 82 so that each roller can move along each groove. Furthermore, the transmission member 82 allows each roller to rotate independently following each groove.

[0100] The screw driver 1A includes a biasing member 84a that moves the transmission member 82 along the second guide groove 46a2 of the guide groove 46a, and a biasing force transmission member 84b that transmits the force with which the biasing member 84a moves the transmission member 82 to the third roller 82c.

[0101] The biasing member 84a is formed of a coil spring or the like, and expands and contracts in the directions of arrows L and R. The switching member 46 has an extension restriction portion 46e with which the biasing member 84a abuts. When the end of the biasing member 84a on the arrow L side abuts against the extension restriction portion 46e, the extension of the biasing member 84a in the direction of arrow L beyond the extension restriction portion 46e is restricted.

[0102] 3D is a side view showing an example of a biasing force transmission member. The biasing force transmission member 84b is an example of a biasing force switching portion, and includes a pressing portion 84c that presses the third roller 82c via the abutted portion 82e, a pressed portion 84d that is pressed by the biasing member 84a, and a position restricting portion 84e that restricts the position of the biasing force transmission member 84b. The biasing force transmission member 84b is supported by the switching member 46 so as to be movable in the directions of arrows L and R. The switching member 46 includes a restricting portion 46d that the position restricting portion 84e abuts against. The restricting portion 46d is an example of a biasing force switching portion, and when the position restricting portion 84e abuts against it, it restricts movement of the biasing force transmission member 84b in the direction of arrow R.

[0103] The biasing member 84a is inserted between the extension restriction portion 46e and the pressed portion 84d. As the compressed biasing member 84a extends in the direction of arrow R, the pressed portion 84d is pressed by the biasing member 84a, and the biasing force transmission member 84b moves in the direction of arrow R. As a result, the pressing portion 84c approaches the first guide groove 46a1 of the guide groove 46a. Furthermore, when the pressed portion 84d is pressed by the biasing member 84a and the position restriction portion 84e moves to a position where it contacts the restriction portion 46d, the amount of movement of the biasing force transmission member 84b in the direction of arrow R is restricted.

[0104] When the position restricting portion 84e of the biasing force transmission member 84b is in contact with the restricting portion 46d, the pressing portion 84c is separated from the abutted portion 82e of the transmission member 82, whose first roller 82a is guided by the first guide groove 46a1. This cancels the transmission of the biasing force from the biasing member 84a to the transmission member 82, which is guided by the first guide groove 46a1 via the first roller 82a. Therefore, when the first roller 82a is guided by the first guide groove 46a1, the transmission member 82 is prevented from being pressed in the direction of arrow R by the biasing member 84a.

[0105] Therefore, the transmission member 82 is prevented from being pressed toward the arrow R side of the first guide groove 46a1 by the biasing member 84a via the first roller 82a, and the sliding resistance when the first roller 82a contacts and moves against the first guide groove 46a1 is reduced. The biasing force of the biasing member 84a on the first roller 82a guided in the second guide groove 46a2 is necessary to move the transmission member 82 in conjunction with the downward movement of the lower arm 80. This biasing force is not necessary while the first roller 82a is guided in the first guide groove 46a1. Therefore, it is sufficient that the biasing force of the biasing member 84a on the first roller 82a guided in the first guide groove 46a1 is weaker than the biasing force of the biasing member 84a on the first roller 82a guided in the second guide groove 46a2. Therefore, the pressing portion 84c may be in contact with the abutted portion 82e as long as the first roller 82a is prevented from being pressed in the direction of arrow R by the biasing member 84a at the position where the first roller 82a is guided in the first guide groove 46a1.

[0106] Furthermore, when the first roller 82a is in the position where it is guided by the second guide groove 46a2, the pressing portion 84c of the force transmission member 84b contacts the abutted portion 82e, and the pressing portion 84c is pressed in the direction of arrow L away from the first guide groove 46a1, compressing the force member 84a in the direction of arrow L.

[0107] As a result, when the first roller 82a is at a position where it is guided by the second guide groove 46a2, the biasing force transmission member 84b presses the transmission member 82 via the first roller 82a by the biasing member 84a in the direction of arrow R. Therefore, the transmission member 82 is biased by the biasing member 84a in a direction in which the first roller 82a moves from the second guide groove 46a2 to the first guide groove 46a1.

[0108] In the screw driving machine 1A, the action of pressing the contact arm 8 against the workpiece 300 causes the lower arm 80 to move upward from the bottom dead center position relative to the main body 10. Within a predetermined range in which the lower arm 80 moves upward from the bottom dead center position, the first roller 82a of the transmission member 82 is guided by the first guide groove 46a1. In the screw driving machine 1A, when the transmission member 82 is in a position in which the first roller 82a is guided by the first guide groove 46a1, the upper arm 81 moves upward in conjunction with the lower arm 80. In the screw driving machine 1A, the movement of the lower arm 80 upward from the bottom dead center position brings the main body 10 and the workpiece 300 relatively closer to each other.

[0109] When the lower arm 80 and the upper arm 81 move to the sign-in position where the starting valve 6 is operable, the first roller 82a of the transmission member 82 is guided by the second guide groove 46a2. When the transmission member 82 is in the position where the first roller 82a is guided by the second guide groove 46a2, the engagement between the lower arm 80 and the upper arm 81 is released. This allows the lower arm 80 to move independently of the upper arm 81.

[0110] Then, when the main valve 5 is activated and the screw 200 is driven into the workpiece 300, the head of the screw 200 is lifted off the workpiece 300 so that the driving depth regulating part 4a regulates the amount of movement of the lower arm 80 from the bottom dead center position between the sign in position and the top dead center position.

[0111] Therefore, the driving depth restricting unit 4a is provided with a locking member 40 that restricts the amount of movement of the lower arm 80 from the bottom dead center position P1. The locking member 40 is supported by a feed member 91 of the screw feed unit 9. The locking member 40 has a locking portion 40b formed at the end on the arrow R side, with which the lower arm 80 abuts.

[0112] The locking member 40 moves between a locking position where the locking portion 40b protrudes into the movement path of the lower arm 80 and a retracted position where the locking portion 40b is retracted from the movement path of the lower arm 80 as the feed member 91 moves.

[0113] The screw driver 1A includes a drive depth adjustment unit 86 that adjusts the drive depth of the screw 200. The drive depth adjustment unit 86 determines the top dead center position of the contact arm 8. When pressed by the contact arm 8, the drive depth adjustment unit 86 activates the first control valve 72.

[0114] The tightening depth adjustment unit 86 is supported so as to be movable in the vertical direction. The tightening depth adjustment unit 86 is biased downward by a biasing member 86c such as a coil spring. The tightening depth adjustment unit 86 is also configured so that the overall length in the vertical direction can be adjusted by operating a dial unit 86d.

[0115] When the lower arm 80 is at the bottom dead center position, the tightening depth adjustment portion 86 is separated from the lower arm 80. When the lower arm 80 moves upward from the bottom dead center position, the tightening depth adjustment portion 86 comes into contact with the lower arm 80.

[0116] Furthermore, before being pushed and moved by the lower arm 80, the tightening depth adjustment unit 86 is separated from the first control valve 72. The lower arm 80 comes into contact with the tightening depth adjustment unit 86 as the lower arm 80 moves upward from the bottom dead center position. When the tightening depth adjustment unit 86 is pushed and moved upward by the lower arm 80, it comes into contact with the first control valve 72.

[0117] Then, the tightening depth adjustment portion 86 is pushed up by the lower arm 80 moving upward, and when it moves to a position where it contacts the movement restriction portion 86e, it restricts the lower arm 80 from moving further upward.

[0118] As a result, the position of the lower arm 80 restricted by the movement of the tightening depth adjusting portion 86 to the position where it contacts the movement restricting portion 86e becomes the top dead center position of the lower arm 80.

[0119] Furthermore, as the overall length of the screwing depth adjustment part 86 changes, the position at which the lower arm 80 abuts moves up and down. This moves the top dead center position of the lower arm 80. When the top dead center position of the lower arm 80 moves, the distance between the main body 10 and the workpiece 300 changes when the rotation of the air motor 31 stops, and the depth at which the screw 200 is screwed into the workpiece 300 changes.

[0120] In addition, the screw driver 1A may not be equipped with the tightening depth adjustment unit 86, and the lower arm 80 may be in direct contact with the first control valve 72, actuating the first control valve 72 and determining the upper fulcrum position of the lower arm 80.

[0121] <Example of operation of the screw driving machine according to this embodiment> Figures 4A and 4B are side cross-sectional views of the main parts of the screw driver of this embodiment, showing an example of the operation of driving a screw into a workpiece and tightening it. Next, an example of the operation of the screw driver 1A that drives and tightens the screw 200 will be described.

[0122] The operator holds the handle portion 11 of the screw driving machine 1A and presses the contact arm 8 against the workpiece 300. When the contact arm 8 is pressed against the workpiece 300, the lower arm 80 of the screw driving machine 1A moves upward relative to the main body 10 in the direction indicated by the arrow U due to the relative movement between the contact arm 8 and the main body 10.

[0123] When the lower arm 80 moves upward, the first engaging portion 88c of the first cam groove 88a of the cam groove 88, which is inclined with respect to the direction of movement of the lower arm 80, presses the second roller 82b.

[0124] When the second roller 82b of the transmission member 82 receives a pushing force from the first engagement portion 88c of the first cam groove 88a of the cam groove 88, the first roller 82a is guided by the first guide groove 46a1 and moves upward.

[0125] When the first roller 82a of the transmission member 82 moves upward, the third roller 82c pushes upward the guide groove 81a of the upper arm 81. As a result, the upper arm 81 moves upward in conjunction with the lower arm 80.

[0126] The position of the upper arm 81 where it can contact the contact lever 60a and activate the contact lever 60a is referred to as the operable position. The lower arm 80 and the upper arm 81 move upward relative to the main body 10, and as shown in Figure 4A, when the lower arm 80 moves to the driving depth setting position P10 where it contacts the locking portion 40b of the locking member 40, the upper arm 81 moves to the operable position. As a result, the contact arm 80 is pressed against the workpiece, and when the lower arm 80 has moved to the driving depth setting position P10 and the trigger 60 is pulled, the contact lever 60a presses the valve stem 62 of the starting valve 6, resulting in a sign-in state in which the starting valve 6 is activated.

[0127] During the operation of pressing the contact arm 8 against the workpiece 300 until the signing state is reached, the first roller 82a of the transmitting member 82 is guided by the first guide groove 46a1. When the transmitting member 82 is in the position where the first roller 82a is guided by the first guide groove 46a1, the position restricting portion 84e of the biasing force transmitting member 84b contacts the restricting portion 46d, and the pressing portion 84c is separated from the abutted portion 82e.

[0128] When the lower arm 80 and the upper arm 81 move upward to a position where signing is possible, the transmission member 82 moves to a position where the first roller 82a is guided by the third guide groove 46a3. When the transmission member 82 is in the position where the first roller 82a is guided by the third guide groove 46a3 of the guide groove 46a, the pressing portion 84c of the biasing force transmission member 84b is separated from the abutted portion 82e. Alternatively, when the transmission member 82 is in the position where the first roller 82a is guided by the third guide groove 46a3, the biasing member 84a is prevented from being compressed even if the pressing portion 84c of the biasing force transmission member 84b comes into contact with the abutted portion 82e.

[0129] As a result, during the operation of pressing the contact arm 8 against the workpiece 300 until the sign-in state is reached, the transmission member 82 is prevented from being pressed in the direction of arrow R by the biasing member 84a. Therefore, the first roller 82a of the transmission member 82 is prevented from being pressed against the first guide groove 46a1 and the third guide groove 46a3 by the biasing member 84a, and sliding resistance when the first roller 82a moves in contact with the first guide groove 46a1 and the third guide groove 46a3 is reduced. Therefore, during the operation of pressing the contact arm 8 against the workpiece 300, the lower arm 80 and the upper arm 81 move upward due to relative movement with respect to the main body 10, and until the sign-in state is reached, the biasing force of the biasing member 84a is prevented from being applied to the lower arm 80 and the upper arm 81 and being transmitted as a load to the operator.

[0130] When the start valve 6 is actuated, the air pressure of the compressed air supplied from the main chamber 13 to the main valve lower chamber 53 moves the main valve 5 upward, connecting the main valve lower chamber 53 and the air flow path 54 so that compressed air can be supplied from the main chamber 13 to the air flow path 54.

[0131] As a result, compressed air is supplied to the second chamber 30d of the striking cylinder 30 from the main chamber 13 via the air flow path 54. The striking piston 30a is pressed by the air pressure of the compressed air supplied to the second chamber 30d of the striking cylinder 30, and moves downward from the top dead center position as indicated by arrow D, moving the driver bit 2 downward along the axial direction. The driver bit 2 and motor shaft 31a move integrally with the striking piston 30a. The driver bit 2 moving downward is guided into the injection passage 12a of the nose portion 12, thereby driving the screw 200 supplied from the magazine 90 to the injection passage 12a into the workpiece 300.

[0132] Furthermore, when the striking piston 30a moves downward from the top dead center position and the second seal portion 30b2 passes through the side hole passage 33b of the striking cylinder 30, compressed air is supplied from the second chamber 30d through the side hole passage 33b to the blowback chamber 33, increasing the pressure inside the blowback chamber 33. When the pressure inside the blowback chamber 33 increases, the pressure inside the feed cylinder 93, which is connected to the blowback chamber 33 via the feed passage 94, also increases, and the air pressure pushes the feed piston 92 in the direction of arrow L. This causes the feed member 91 connected to the feed piston 92 to move in the direction of arrow L.

[0133] When the feed member 91 moves in the direction of arrow L, the locking member 40 attached to the feed member 91 also moves in the direction of arrow L. As a result, the locking member 40 moves to a retracted position where the locking portion 40b is retracted from the movement path of the lower arm 80, as shown in Fig. 4B. When the locking member 40 moves to the retracted position, the action of pressing the contact arm 8 against the workpiece 300 causes the lower arm 80 to move upward relative to the main body 10 beyond the driving depth specification position P10.

[0134] Furthermore, when the main valve 5 operates, compressed air is supplied from the main chamber 13 to the on-off valve lower chamber 73a of the on-off valve cylinder 73, which is the space below the on-off valve 7, via the air flow path 54. When compressed air is supplied to the on-off valve lower chamber 73a, the on-off valve 7 is operated by the air pressure and moves upward, connecting the air flow path 54 and the air flow path 74. As a result, compressed air is supplied to the air motor 31.

[0135] When compressed air is supplied to the air motor 31, the driver bit 2 rotates, and the screw 200 driven into the workpiece 300 is tightened. In addition, by pressing the contact arm 8 against the workpiece 300, the main body 10 moves further downward in response to the tightening of the screw 200.

[0136] When the lower arm 80 moves upward relative to the main body 10 beyond the driving depth specified position P10, the second roller 82b of the transmission member 82 is pushed by the first engagement portion 88c of the cam groove 88, causing the first roller 82a to move from the first guide groove 46a1 of the switching member 46 to the second guide groove 46a2.

[0137] When the second roller 82b of the transmission member 82 receives a further pressing force from the first engagement portion 88c, the first roller 82a is guided by the second guide groove 46a2, and moves laterally in the direction indicated by arrow L. Furthermore, when the upper arm 81 moves to the operable position, it comes into contact with the support protrusion 83c to which the biasing member 83b is attached. The support protrusion 83c is fixed in position relative to the main body 10. This restricts the upper arm 81 from moving upward even if the lower arm 80 moves upward relative to the main body 10. Therefore, the interlocking engagement between the lower arm 80 and the upper arm 81 via the transmission member 82 is released, and the upper arm 81 moves to the operable position. While the first roller 82a is positioned in the second guide groove 46a2, the position of the upper arm 81 is maintained in the operable position.

[0138] Furthermore, when the first roller 82a is in the position where it is guided by the second guide groove 46a2, the pressing portion 84c of the force transmission member 84b contacts the abutted portion 82e, and the pressing portion 84c is pressed in the direction of arrow L away from the first guide groove 46a1, compressing the force member 84a in the direction of arrow L.

[0139] When the lower arm 80 has moved to the bottom dead center position, the control unit 70 determines that the lower arm 80 is not in contact with the tightening depth adjustment unit 86, and therefore the tightening depth adjustment unit 86 is not in contact with the first control valve 72. When the tightening depth adjustment unit 86 is not in contact with the first control valve 72, the first control valve 72 is urged by the first urging member 72b to move to the standby position P100, and the second control valve 71 is urged by the second urging member 71a to move to the standby position P110.

[0140] When the contact arm 8 is pressed against the workpiece 300, the main body 10 moves further downward in response to the tightening of the screw 200, and the lower arm 80 moves relatively upward, the lower arm 80 comes into contact with the tightening depth adjustment part 86 and pushes the tightening depth adjustment part 86 upward.

[0141] The tightening depth adjustment portion 86 is pushed up by the lower arm 80 moving upward, and when the tightening depth adjustment portion 86 moves to a position where it contacts the movement restricting portion 86e, further upward movement of the lower arm 80 is restricted. When the tightening depth adjustment portion 86 moves to a position where it contacts the movement restricting portion 86e and the lower arm 80 moves to the top dead center position, the lower arm 80 pushes the first control valve 72 upward via the tightening depth adjustment portion 86, and the first control valve 72 moves from the standby position P100 to the pressure control start position.

[0142] The third chamber 75a of the control valve cylinder 75 is always in communication with the space within the striking cylinder 30 via the communication passage 75c and the side hole flow passage 32a of the striking cylinder 30. When the main valve 5 is actuated and the striking piston 30a moves downward a predetermined distance, the second seal portion 30b2 passes through the side hole flow passage 32a, and the second chamber 30d within the striking cylinder 30 and the third chamber 75a of the control valve cylinder 75 are in communication with each other. This allows compressed air to be supplied from the second chamber 30d to the timer chamber 32. However, during the period from when the first control valve 72 is in standby at the standby position P100 to when it moves to the pressure control start position, the seal portion 72c of the first control valve 72 is in a position that opens the exhaust path 75d, and the third chamber 75a of the control valve cylinder 75 is in communication with the outside of the machine body of the screw driving tool 1A via the exhaust path 75d. As a result, even if compressed air is supplied from the timer chamber 32 to the third chamber 75a of the control valve cylinder 75, the third chamber 75a is maintained at atmospheric pressure, and the first control valve 72 does not operate with air pressure.

[0143] When the first control valve 72 moves to the pressure control start position, the seal portion 72c of the first control valve 72 blocks the exhaust path 75d. When the air flow path to the outside through the exhaust path 75d is blocked, the pressure inside the control valve cylinder 75 increases due to the air pressure of the compressed air supplied from the timer chamber 32 to the third chamber 75a of the control valve cylinder 75. When the pressure inside the control valve cylinder 75 increases, the air pressure activates the first control valve 72, causing the first control valve 72 to move further upward.

[0144] When the first control valve 72 moves further upward from the pressure control start position due to the air pressure of the compressed air and moves to the second control valve operation start position, the first control valve 72 comes into contact with the second control valve 71 and pushes the second control valve 71 upward. When the second control valve 71 moves to the operation end position as a result of the first control valve 72 moving to the operation end position, compressed air is supplied to the on-off valve upper chamber 73b of the on-off valve cylinder 73, which is the space above the on-off valve 7.

[0145] When compressed air is supplied to the on-off valve upper chamber 73b, the on-off valve 7 moves downward due to the difference in pressure acting on the on-off valve 7 by the compressed air supplied to the on-off valve upper chamber 73b and the pressure acting on the on-off valve 7 by the compressed air supplied to the on-off valve lower chamber 73a, and the supply of compressed air to the air motor 31 stops. When the supply of compressed air to the air motor 31 stops, the rotation of the driver bit 2 stops.

[0146] When the rotation of the driver bit 2 stops and the screw 200 has been tightened, the worker reduces the force pressing the contact arm 8 against the workpiece 300 and moves the main body 10 in a direction away from the workpiece 300.

[0147] When the main body 10 moves in a direction away from the workpiece 300, the main body 10 and the lower arm 80 move relative to each other, and the lower arm 80 moves in the direction of arrow D from the top dead center position due to the biasing force of the biasing member 83a.

[0148] When the lower arm 80 has moved to the top dead center position, the transmission member 82 has moved to a position where the first roller 82a is guided by the second guide groove 46a2. When the first roller 82a is guided by the second guide groove 46a2, the pressing portion 84c of the biasing force transmission member 84b comes into contact with the abutted portion 82e, and the pressing portion 84c is pressed in the direction of arrow L, compressing the biasing member 84a in the direction of arrow L.

[0149] As a result, when the lower arm 80 moves downward from the top dead center position, the inclination of the first engagement portion 88c and the second engagement portion 88d of the cam groove 88 allows the second roller 82b to move in the direction of arrow R. Then, the first roller 82a of the transmission member 82 is guided by the second guide groove 46a2 by the biasing force caused by the extension of the biasing member 84a, and moves in the direction of arrow R.

[0150] This prevents the biasing force of the biasing member 84a from becoming a load until the signed-in state is reached when the contact arm 8 is pressed against the workpiece 300. Also, when the lower arm 80 moves downward from the top dead center position, the first roller 82a can be reliably moved from the second guide groove 46a2 to the first guide groove 46a1 of the guide groove 46a, and the upper arm 81 can be reliably returned to a state where it moves in conjunction with the movement of the lower arm 80.

[0151] When the first roller 82a moves from the second guide groove 46a2 to the first guide groove 46a1, the transmission member 82 is guided by the first guide groove 46a1 and becomes movable downward. As a result, the upper arm 81 moves downward relative to the main body 10, following the lower arm 80 due to the biasing force of the biasing member 83b.

[0152] When the upper arm 81 moves downward, the pressure on the contact lever 60a is released, and the contact lever 60a moves away from the starting valve 6. When the contact lever 60a moves away from the starting valve 6, the main valve 5 closes, and the second chamber 30d of the striking cylinder 30 communicates with the atmosphere via the air flow path 54 and the exhaust pipe 14, causing the pressure in the second chamber 30d to decrease.

[0153] When the pressure in the second chamber 30d of the striking cylinder 30 drops to atmospheric pressure, the air pressure in the blowback chamber 33 moves the striking piston 30a to the top dead center position. When the striking piston 30a moves to the top dead center position, the pressure in the blowback chamber 33 drops, and the feed member 91 connected to the feed piston 92 moves in the direction of arrow R due to the biasing force of the biasing member 94a.

[0154] When the feed member 91 moves in the direction of arrow R, a feed pawl (not shown) provided on the feed member 91 feeds the next screw 200 to the injection passage 12a. Also, the locking member 40 attached to the feed member 91 moves in the direction of arrow R. As a result, the locking member 40 moves to a locking position where the locking portion 40b protrudes into the movement path of the lower arm 80B.

[0155] In addition, the cam groove 88 is provided with a second cam groove 88b, thereby ensuring a range in which the second roller 82b can move relative to the cam groove 88 when adjusting the upper fulcrum position of the lower arm 80 using the tightening depth adjustment unit 86.

[0156] <Configuration example of the screw driving machine according to the present embodiment equipped with a screw driving depth switching unit> Figures 5A and 5B are side cross-sectional views of essential parts of an example of a screw driver of this embodiment equipped with a screw driving depth switching unit, Figure 5C is a side view of an example of a screw driver of this embodiment equipped with a screw driving depth switching unit, Figures 5D and 5E are bottom cross-sectional views of essential parts of an example of a screw driver of this embodiment equipped with a screw driving depth switching unit, and Figure 6 is an oblique view of essential parts of an example of a screw driver of this embodiment equipped with a screw driving depth switching unit.

[0157] 5A, 5D, and 6 show the states of the various components when a first mode is selected, in which the screw driving depth is set to a first driving depth. Also, FIGS. 5B and 5E show the states of the various components when a second mode is selected, in which the screw driving depth is set to a second driving depth that is deeper than the first driving depth. Note that in screw driver 1B, which is equipped with a screw driving depth switching unit, components with the same configuration as screw driver 1A, which is not equipped with a driving depth switching unit, will be described with the same reference numerals.

[0158] The screw driver 1B includes a driving depth switching unit 4b that switches between restricting the driving depth of the screw 200 by the driving depth restricting unit 4a and not restricting the driving depth of the screw 200.

[0159] The driving depth restricting unit 4a includes a locking member 48 that restricts the amount of movement of the lower arm 80B from the bottom dead center position P1. The driving depth switching unit 4b also includes a switching member 47 that switches between restricting the amount of movement of the lower arm 80B by the locking member 48 and not restricting it. The switching member 47 is an example of a guide unit, and also has the function of guiding the movement path of the transmission member 82 via the first roller 82a and switching between interlocking the lower arm 80B and the upper arm 81 and not interlocking them.

[0160] In addition, the driving depth switching unit 4b is provided with a switching operation member 42 that activates the switching member 47 and switches the bottom dead center position of the lower arm 80B between the first bottom dead center position P1 shown in Figure 5A and the second bottom dead center position P2 shown in Figure 5B.

[0161] 7A is a side view showing an example of a lower arm of a screw driver equipped with a driving depth switching unit. Lower arm 80B has the above-mentioned cam groove 88 that moves transmission member 82 via second roller 82b. Lower arm 80B also has bottom dead center position switching acted upon portion 85 that receives a force from switching operation member 42 that moves lower arm 80B upward.

[0162] 7B is a side view showing an example of a switching member of a screw driver equipped with a driving depth switching unit. Switching member 47 has the above-mentioned guide groove 46a that guides first roller 82a to move transmission member 82 to a predetermined position. Switching member 47 also has an actuating unit 46b that actuates locking member 48 and switches between restricting and not restricting the amount of movement of lower arm 80B by locking member 48. Switching member 47 also has an acted-on unit 46c that receives a force that moves switching member 47 in the directions of arrows L and R.

[0163] The switching operation member 42 includes an action portion 42a that moves the lower arm 80B and the switching member 47 in conjunction with each other, and an operation portion 42b that is operated by a person.

[0164] The acting portion 42a has a first cam surface 42a1 that comes into contact with the bottom dead center position switching acted upon portion 85 of the lower arm 80B and moves the lower arm 80B upward. The acting portion 42a also has a second cam surface 42a2 that comes into contact with the acted upon portion 46c of the switching member 47 and moves the switching member 47 in the directions indicated by arrows L and R.

[0165] The operating portion 42b is connected to the shaft 42c and rotates the acting portion 42a around the shaft 42c. When the operating portion 42b is operated, the acting portion 42a rotates around the shaft 42c, and the first cam surface 42a1 of the switching operating member 42 is displaced, thereby moving the lower arm 80B upward. Furthermore, the second cam surface 42a2 is displaced, thereby moving the switching member 47 in the directions indicated by arrows L and R.

[0166] The locking member 48 is supported by the feed member 91 of the screw feed unit 9 so as to be rotatable about the shaft 40a as a fulcrum. The locking member 48 has a locking portion 40b formed at its end on the arrow R side across the shaft 40a, which is locked to the lower arm 80B. The locking member 48 also has an acted upon portion 40c formed at its end on the arrow L side across the shaft 40a, against which the operating portion 46b comes into contact as the switching member 47 moves. The locking member 48 is urged by an urging member 40d, such as a coil spring, in a direction in which the locking portion 40b protrudes into the movement path of the lower arm 80 as it rotates about the shaft 40a as a fulcrum.

[0167] As shown in Fig. 5D, locking member 48 moves by rotation about shaft 40a between a locking position where locking portion 40b protrudes into the movement path of lower arm 80B and a first retracted position where locking member 48 is retracted from the movement path of lower arm 80B by movement of switching member 47 without movement of feed member 91 as shown in Fig. 5E. Locking member 48 also moves between the above-mentioned locking position and a second retracted position where locking member 48 is retracted from the movement path of lower arm 80B by movement of feed member 91 without movement of switching member 47. Furthermore, after locking member 48 has moved to the first retracted position by movement of switching member 47, locking member 48 moves between the first and second retracted positions by movement of feed member 91.

[0168] As a result, the driving depth switching unit 4b switches between restricting and not restricting the amount of movement of the lower arm 80B by moving the locking member 48 via the switching member 47. Furthermore, the driving depth switching unit 4b moves the transmission member 82 via the switching member 47 in conjunction with switching between restricting and not restricting the amount of movement of the lower arm 80B by moving the switching member 47. Then, since the pressed portion 84d is in contact with the restricting portion 46d of the switching member 47, the biasing force transmission member 84b moves in conjunction with the movement of the switching member 47, and the biasing member 84a moves in conjunction with the movement of the biasing force transmission member 84b.

[0169] <An example of changing the screw driving depth> By operating the switching operation member 42, the screw driver 1B can be switched between a first mode in which the driving depth of the screw 200 is a first driving depth, and a second mode in which the driving depth of the screw 200 is deeper than the first driving depth.

[0170] In the first mode, the operating portion 42b operates the switching operation member 42, causing the acting portion 42a to rotate in the direction of arrow C1. With the acting portion 42a rotated in the direction of arrow C1, the first cam surface 42a1 is separated from the bottom dead center position switching acted portion 85 of the lower arm 80B. As a result, the lower arm 80B is biased downward by the biasing member 83a, and is placed on standby in a state where it has moved to the first bottom dead center position P1, as shown in FIG. 5A.

[0171] Furthermore, when the acting portion 42a is rotated in the direction of arrow C1, the second cam surface 42a2 presses the acted-on portion 46c of the switching member 47 in the direction of arrow R. This causes the switching member 47 to move in the direction of arrow R. The position of the switching member 47 when the first mode is selected is referred to as a first guide position P21.

[0172] When the lower arm 80 is waiting at the first bottom dead center position P1 and the switching member 47 is moving to the first guide position P21, the operating portion 46b is moving in a direction away from the acted-on portion 40c of the locking member 48. As a result, the locking member 48 is moved to a locking position where the locking portion 40b protrudes into the movement path of the lower arm 80B, as shown in FIG.

[0173] Furthermore, when the lower arm 80B is waiting at the first bottom dead center position P1 and the switching member 47 is moving to the first guide position P21, the transmission member 82 is moving to a position where the first roller 82a is guided by the first guide groove 46a1 of the switching member 47.

[0174] In this state, the biasing force transmission member 84b is biased by the biasing member 84a to move to a position where the position restricting portion 84e contacts the restricting portion 46d. When the biasing force transmission member 84b moves to a position where the position restricting portion 84e contacts the restricting portion 46d, the biasing force of the biasing member 84a restricts the pressing portion 84c from moving further in the direction of arrow R.

[0175] As a result, the pressing portion 84c of the biasing force transmission member 84b moves away from the abutted portion 82e. Therefore, when the lower arm 80B is waiting at the first bottom dead center position P1 and the switching member 47 is moved to the first guide position P21, the transmission member 82 prevents the first roller 82a from being pressed against the first guide groove 46a1 by the biasing member 84a.

[0176] To switch from the first mode to the second mode, the bottom dead center position of the lower arm 80B is raised from the first bottom dead center position P1 shown in FIG. 5A to the second bottom dead center position P2 shown in FIG. 5B, and the locking portion 40b of the locking member 48 is moved to a first retracted position retracted from the movement path of the lower arm 80B.

[0177] Therefore, in the second mode, the operating portion 42b is operated to rotate the acting portion 42a of the switching operation member 42 in the direction of arrow C2. When the acting portion 42a rotates in the direction of arrow C2, the second cam surface 42a2 presses the acted-on portion 46c of the switching member 47 in the direction of arrow L. This causes the switching member 47 to move in the direction of arrow L. The position of the switching member 47 when the second mode is selected is referred to as a second guide position P22.

[0178] When the switching member 47 moves in the direction of arrow L from the first guide position P21 to the second guide position P22, the first roller 82a of the transmission member 82 is pushed in the direction of arrow L by the first guide groove 46a1 of the switching member 47, and the transmission member 82 moves in the direction of arrow L.

[0179] Furthermore, when the acting portion 42a rotates in the direction of arrow C2, the first cam surface 42a1 comes into contact with the bottom dead center position switching acted portion 85 of the lower arm 80B and pushes up the bottom dead center position switching acted portion 85. This causes the lower arm 80B to move upward.

[0180] In this way, the switching operation member 42 moves the lower arm 80B upward. When the lower arm 80B moves upward, the inclination of the first cam groove 88a of the cam groove 88 generates a force that moves the transmission member 82 upward via the second roller 82b, and a force that moves the transmission member 82 in the direction of arrow L.

[0181] In response to this, the switching operation member 42 moves the transmission member 82 in the direction of arrow L via the first roller 82a by the switching member 47 in conjunction with the movement of the lower arm 80B. This prevents the transmission member 82 from moving upward even if the lower arm 80B moves upward. Therefore, the third roller 82c is prevented from pressing upward against the guide groove 81a of the upper arm 81, and the upper arm 81 is prevented from moving upward.

[0182] Therefore, the engagement of the lower arm 80B with the upper arm 81 via the transmission member 82 is released, and the lower arm 80B moves upward independently of the upper arm 81. Then, the lower arm 80B moves to the second bottom dead center position P2 as shown in FIG. 5B.

[0183] In the second mode, the amount of upward movement of the upper arm 81 when the lower arm 80B moves to the second bottom dead center position P2 is an amount that prevents the upper arm 81 from moving to an operable position that activates the contact lever 60a of the trigger 60. As a result, in the second mode, the pressing member 87 operated by the upper arm 81 waits in a position closer to the contact lever 60a than in the first mode.

[0184] Therefore, in the second mode, the contact arm 8 is pressed against the workpiece 300, and the upper arm 81 moves to an operable position that activates the contact lever 60a of the trigger 60, and the movement of the upper arm 81 until it reaches the sign-in state can be made smaller than when the position of the upper arm 81 is not changed from the state in the first mode, thereby further improving the operating feel.

[0185] In the screw driver 1B, the guide groove 81a of the upper arm 81 is connected to the cam groove 88 of the lower arm 80B and the guide groove 46a of the switching member 47 by a transmission member 82, and the upper arm 81 is urged downward by a biasing member 83b. Furthermore, in the screw driver 1B, the lower arm 80B is urged downward by the biasing member 83a, and in the second mode, when the contact arm 8 is not pressed against the workpiece 300, the first cam surface 42a1 of the acting portion 42a comes into contact with the bottom dead center position switching acted portion 85 of the lower arm 80B, and the lower arm 80B is supported at the second bottom dead center position P2. As a result, in the second mode, even when the contact arm 8 is not pressed against the workpiece 300 and the second roller 82b is in contact with the middle of the first engagement portion 88c of the first cam groove 88a, which is formed by the slope of the cam groove 88, the lower arm 80B can be fixed at the second bottom dead center position P2.

[0186] As described above, when the lower arm 80B is waiting at the first bottom dead center position P1 and the switching member 47 is moving to the first guide position P21, the biasing force transmission member 84b is biased by the biasing member 84a to move to a position where the position restricting portion 84e contacts the restricting portion 46d. When the switching member 47 moves from this state in the direction of arrow L from the first guide position P21 to the second guide position P22, the biasing force transmission member 84b moves in the direction of arrow L in conjunction with the switching member 47. Furthermore, even when the lower arm 80B is waiting at the second bottom dead center position P2 and the switching member 47 is moving to the second guide position P22, the transmission member 82 has moved to a position where the first roller 82a is guided by the first guide groove 46a1.

[0187] As a result, the pressing portion 84c of the biasing force transmission member 84b moves away from the abutted portion 82e. Therefore, even when the lower arm 80B is waiting at the second bottom dead center position P2 and the switching member 47 is moved to the second guide position P22, the first roller 82a of the transmission member 82 is prevented from being pressed against the first guide groove 46a1 of the guide groove 46a by the biasing member 84a.

[0188] <Example of operation of the screw driving machine equipped with the screw driving depth switching unit according to this embodiment> 8A and 8B are side cross-sectional views of the main parts of the screw driver of this embodiment, showing an example of the operation of driving a screw into a workpiece and tightening it when the first mode is selected. Also, Fig. 9 is a side cross-sectional view of the main parts of the screw driver of this embodiment, showing an example of the operation of driving a screw into a workpiece and tightening it when the second mode is selected. Next, an example of the operation of the screw driver 1B that drives and tightens the screw 200 will be described.

[0189] The operation of the screw driver 1B, which selects the first mode and drives and tightens the screw 200, is similar to that of the screw driver 1A.

[0190] When the first mode is selected, during the operation of pressing the contact arm 8 against the workpiece 300 until the sign-in state is reached, when the first roller 82a is guided by the first guide groove 46a1, the position regulating portion 84e of the force transmission member 84b is in contact with the regulating portion 46d, and the pressing portion 84c is separated from the abutted portion 82e.

[0191] When the lower arm 80B and the upper arm 81 move upward to a position where signing is possible, the first roller 82a moves to a position where it is guided by the third guide groove 46a3, as shown in Fig. 8A. When the transmitting member 82 is in the position where the first roller 82a is guided by the third guide groove 46a3, the pressing portion 84c of the biasing force transmitting member 84b is separated from the abutted portion 82e. Alternatively, when the transmitting member 82 is in the position where the first roller 82a is guided by the third guide groove 46a3, the biasing member 84a is prevented from being compressed even if the pressing portion 84c of the biasing force transmitting member 84b comes into contact with the abutted portion 82e.

[0192] Therefore, when the first mode is selected, during the operation of pressing the contact arm 8 against the workpiece 300 until the sign-in state is reached, the first roller 82a of the transmission member 82 is prevented from being pressed against the first guide groove 46a1 and the third guide groove 46a3 by the biasing member 84a. This reduces sliding resistance when the first roller 82a moves in contact with the first guide groove 46a1 and the third guide groove 46a3. Therefore, during the operation of pressing the contact arm 8 against the workpiece 300 until the lower arm 80B and the upper arm 81 move upward due to relative movement with respect to the main body 10 and the sign-in state is reached, the biasing force of the biasing member 84a is applied to the lower arm 80B and the upper arm 81, and is prevented from being transmitted as a load to the operator.

[0193] 8B, when the lower arm 80 has moved to the top dead center position, the transmission member 82 has moved to a position where the first roller 82a is guided by the second guide groove 46a2. When the first roller 82a is guided by the second guide groove 46a2, the pressing portion 84c of the biasing force transmission member 84b comes into contact with the abutted portion 82e, and the pressing portion 84c is pressed in the direction of arrow L, compressing the biasing member 84a in the direction of arrow L.

[0194] When the screw 200 has been tightened and the main body 10 is moved in a direction away from the workpiece 300, the main body 10 and the lower arm 80B move relative to each other, causing the lower arm 80 to move downward from the top dead center position. When the lower arm 80 moves downward from the top dead center position, the second roller 82b becomes movable in the direction of arrow R due to the inclination of the first engagement portion 88c and the second engagement portion 88d of the cam groove 88. Then, the first roller 82a of the transmission member 82 is guided by the second guide groove 46a2 by the biasing force generated by the extension of the biasing member 84a, and moves in the direction of arrow R.

[0195] Therefore, when the lower arm 80 moves downward from the top dead center position, the first roller 82a can be reliably moved from the second guide groove 46a2 of the guide groove 46a to the first guide groove 46a1, and the upper arm 81 can be reliably returned to a state in which it moves in conjunction with the movement of the lower arm 80.

[0196] Next, an example of the operation of the screw driver 1A in which the second mode is selected and the screw 200 is driven and tightened will be described.

[0197] When the second mode is selected in the screw driving tool 1B, as described above, the lower arm 80B moves to the second bottom dead center position P2. Also, the locking member 48 moves to the first retracted position where the locking portion 40b is retracted from the movement path of the lower arm 80 due to the movement of the switching member 47.

[0198] With the second mode selected in this manner, the operator holds the handle 11 of the screw driving tool 1B and presses the contact arm 8 against the workpiece 300. When the contact arm 8 of the screw driving tool 1B is pressed against the workpiece 300, the lower arm 80B moves upward relative to the main body 10.

[0199] When the lower arm 80B is moved to the second bottom dead center position P2, the transmitting member 82 is moved to a position where the first roller 82a is guided by the first guide groove 46a1. As a result, when the lower arm 80B moves upward from the second bottom dead center position P2 by relative movement with respect to the main body 10, the second roller 82b is pressed by the cam groove 88 of the lower arm 80B, and the first roller 82a is guided by the first guide groove 46a1 of the guide groove 46a of the switching member 47, causing the transmitting member 82 to move upward.

[0200] When the transmission member 82 moves upward, it pushes upward the guide groove 81a of the upper arm 81. As a result, the upper arm 81 moves upward in the direction indicated by the arrow U in conjunction with the lower arm 80B.

[0201] When the lower arm 80B and the upper arm 81 move upward relative to the main body 10, the lower arm 80B moves upward beyond the locking member 48 that has moved to the first retracted position.

[0202] 9, when the lower arm 80B moves to the top dead center position, the upper arm 81 moves to an operable position where it operates the contact lever 60a of the trigger 60. When the upper arm 81 moves to the operable position, it comes into contact with the support protrusion 83c to which the biasing member 83b is attached.

[0203] When the second mode is selected, the upper arm 81 moves to the operable position, the lower arm 80B moves to the top dead center position, and when the trigger 60 is pulled, the start valve 6 enters a sign-in state in which it operates.

[0204] When the second mode is selected, during the operation of pressing the contact arm 8 against the workpiece 300 until the sign-in state is reached, the position restricting portion 84e of the biasing force transmission member 84b is in contact with the restricting portion 46d, and the pressing portion 84c is separated from the abutted portion 82e. Furthermore, when the lower arm 80B moves to the top dead center position, the transmission member 82 moves to a position where the first roller 82a is guided by the third guide groove 46a3. When the transmission member 82 is in the position where the first roller 82a is guided by the third guide groove 46a3, the pressing portion 84c of the biasing force transmission member 84b is separated from the abutted portion 82e. Alternatively, at the position of the transmission member 82 where the first roller 82a is guided by the third guide groove 46a3 of the guide groove 46a, the biasing force transmission member 84b prevents the biasing member 84a from being compressed even if the pressing portion 84c contacts the abutted portion 82e.

[0205] As a result, the first roller 82a of the transmission member 82 is prevented from being pressed against the first guide groove 46a1 and the third guide groove 46a3 by the biasing member 84a, and sliding resistance when the first roller 82a moves in contact with the first guide groove 46a1 and the third guide groove 46a3 is reduced. Therefore, even when the second mode is selected, the biasing force of the biasing member 84a is applied to the lower arm 80B and the upper arm 81 and is prevented from being transmitted as a load to the operator until the lower arm 80B and the upper arm 81 move upward due to relative movement with respect to the main body 10 during the operation of pressing the contact arm 8 against the workpiece 300 and reach the sign-in state.

[0206] When the start valve 6 is actuated, the main valve 5 is actuated as described above, and compressed air is supplied to the striking cylinder 30, causing the striking piston 30a to move downward from the top dead center position, thereby driving the screw 200 supplied to the injection passage 12a into the workpiece 300.

[0207] Furthermore, when the striking piston 30a moves downward from the top dead center position, the feed member 91 connected to the feed piston 92 moves in the direction of arrow L, causing the locking member 48 attached to the feed member 91 to move in the direction of arrow L. As a result, the locking member 48, while still in the first retracted position, moves to the second retracted position.

[0208] Furthermore, when the main valve 5 is operated, compressed air is supplied to the air motor 31, causing the driver bit 2 to rotate and tightening the screw 200 that has been driven into the workpiece 300. Furthermore, by pressing the contact arm 8 against the workpiece 300, the main body 10 moves further downward in response to the tightening of the screw 200.

[0209] As described above, when the second mode is selected, when the lower arm 80B moves to the top dead center position, sign-in becomes possible and the striking piston 30a starts to move downward. Therefore, the on-off valve 7 is configured not to operate until the striking piston 30a moves downward a predetermined distance.

[0210] Then, when the striking piston 30a moves downward a predetermined distance, the on-off valve 7 operates as described above, and the supply of compressed air to the air motor 31 is stopped. When the supply of compressed air to the air motor 31 is stopped, the rotation of the driver bit 2 is stopped.

[0211] When the rotation of the driver bit 2 stops and the screw 200 has been tightened, the worker reduces the force pressing the contact arm 8 against the workpiece 300 and moves the main body 10 in a direction away from the workpiece 300.

[0212] When the main body 10 moves in a direction away from the workpiece 300, the main body 10 and the lower arm 80B move relative to each other, and the lower arm 80B moves downward from the top dead center position due to the biasing force of the biasing member 83a.

[0213] When the second mode is selected, with the lower arm 80B having moved to the top dead center position, the first roller 82a has moved to a position where it is guided by the third guide groove 46a3, as described above. When the transmission member 82 is at a position where the first roller 82a is guided by the third guide groove 46a3 of the guide groove 46a, no force is applied from the biasing member 84a to the transmission member 82 in the direction of arrow R via the biasing force transmission member 84b.

[0214] However, since the transmission member 82 has moved to a position where the first roller 82a is guided by the third guide groove 46a3 of the guide groove 46a, when the lower arm 80B moves in the direction of arrow D from the top dead center position, the inclination of the cam groove 88 of the lower arm 80B causes the first roller 82a to be guided by the third guide groove 46a3 and move in the direction of arrow R.

[0215] As a result, when the second mode is selected, the first roller 82a can be reliably moved from the third guide groove 46a3 to the first guide groove 46a1 by the action of the lower arm 80B moving downward from the top dead center position.

[0216] When the first roller 82a moves from the third guide groove 46a3 to the first guide groove 46a1, the transmission member 82 is guided by the first guide groove 46a1 and becomes movable downward. As a result, the upper arm 81 moves downward relative to the main body 10, following the lower arm 80B due to the biasing force of the biasing member 83b.

[0217] When the upper arm 81 moves downward, the pressure on the contact lever 60a is released, and the contact lever 60a moves away from the starting valve 6. When the contact lever 60a moves away from the starting valve 6, the main valve 5 closes, and the air pressure in the blowback chamber 33 moves the striking piston 30a to the top dead center position. When the striking piston 30a moves to the top dead center position, the feed member 91 connected to the feed piston 92 moves in the direction of arrow R due to the biasing force of the biasing member 94a.

[0218] When the feed member 91 moves in the direction of arrow R, a feed pawl (not shown) provided on the feed member 91 feeds the next screw 200 to the injection passage 12a. Also, the locking member 48 attached to the feed member 91 moves in the direction of arrow R. As a result, the locking member 48 moves from the second retracted position to the first retracted position. [Explanation of symbols]

[0219] 1A, 1B... screw driver, 10... main body, 11... handle, 12... nose, 12a... injection passage, 12b... injection port, 12c... blocking section, 12d... introduction section, 13... main chamber, 14... exhaust pipe, 2... driver bit, 30... striking cylinder (driving section), 30a... striking piston, 31... air motor (tightening section), 31a... motor shaft, 31d... reducer, 32... timer chamber, 32a... Side hole flow passage, 33 Blowback chamber, 33a, 33b Side hole flow passage, 34 Supply port, 4a Driving depth restricting portion, 4b Driving depth switching portion, 40, 48 Locking member, 40b Locking portion, 40c Acting portion, 46, 47 Switching member (guide portion), 46a Guide groove, 46a1 First guide groove, 46a2 Second guide groove, 46a3 Third guide groove, 46d Restricting portion, 42 Switching operation member, 5 1. Main valve, 6. Starting valve, 60. Trigger, 7. On-off valve, 70. Control unit, 8. Contact arm (contact unit), 80, 80B. Lower arm (first arm), 81. Upper arm (second arm), 81a. Guide groove, 82. Transmission member, 82a. First roller, 82b. Second roller, 82c. Third roller, 82d. Shaft, 82e. Contacted portion, 84a. Biasing member, 84b. Biasing force transmission member, 84 c Pressing portion, 84d Pressed portion, 84e Position restricting portion, 85 Bottom dead center position switching acted upon portion, 86 Fastening depth adjusting portion, 88 Cam groove, 88a First cam groove, 88b Second cam groove, 88c First engaging portion, 88d Second engaging portion, 9 Screw feed portion, 90 Magazine, 91 Feed member, 92 Feed piston, 93 Feed cylinder, 200 Screw, 201 Connecting band, 300 Material to be driven

Claims

1. a driving section to which compressed air is supplied and which moves the driver bit in the axial direction; a tightening portion to which compressed air is supplied and which rotates the driver bit around its axis; a main valve for switching on and off the supply of compressed air to the driving portion and the tightening portion; a starting valve for actuating the main valve; a first arm supported movably along the axial direction of the driver bit and in contact with the workpiece; a second arm supported movably along the axial direction of the driver bit and configured to actuate the starting valve; a transmission member that moves the first arm to a position where the movement of the first arm can be transmitted to the second arm, thereby interlocking the first arm and the second arm, and moves the first arm to a position where the movement of the first arm is not transmitted to the second arm, thereby releasing the interlocking of the first arm and the second arm; a guide unit that guides movement of the transmission member and switches between interlocking and non-interlocking of the first arm and the second arm depending on the position of the transmission member that it is guiding; a biasing member that biases the transmission member toward a position where the movement of the first arm can be transmitted to the second arm; a biasing force switching section that regulates the biasing force of the biasing member on the transmission member and switches the strength of the biasing force of the biasing member depending on the position of the transmission member guided by the guide section; A screw driver equipped with

2. The biasing force switching unit is a biasing force transmission member that transmits the biasing force of the biasing member to the transmission member; a restricting portion that restricts the position of the biasing force transmission member; The screw driver according to claim 1.

3. The transmission member is composed of a roller. The screw driver according to claim 2.

4. The guide portion is a first guide groove including a position where movement of the first arm can be transmitted to the second arm, and guiding the transmission member in a direction that interlocks the first arm and the second arm; a second guide groove that guides the transmission member in a direction that includes a position where the movement of the first arm is not transmitted to the second arm and that releases the interlocking of the first arm and the second arm; The biasing force switching unit is The biasing force of the biasing member on the transmission member guided by the first guide groove is made weaker than the biasing force of the biasing member on the transmission member guided by the second guide groove. The screw driver according to claim 2.

5. The biasing force switching unit is The transmission of the biasing force by the biasing member to the transmission member guided by the first guide groove is released. The screw driver according to claim 4.

6. a driving depth limiting unit that limits the movement amount of the first arm to limit the depth to which the screw is driven by the driving unit; a driving depth switching unit that switches between restricting the movement amount of the first arm by the driving depth restricting unit and moving the transmission member via the guide unit in conjunction with the switching between restricting the movement amount of the first arm, The biasing force switching portion and the biasing member move in conjunction with the movement of the guide portion. The screw driver according to claim 4.

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