Driving tool

Abstract

To provide a screw driving machine that can properly keep air pressure in a striking cylinder, without inhibiting a function of guiding a driver.SOLUTION: A screw driving machine 1A is provided with: a striking cylinder 30 that is supplied with compressed air; a striking piston 30a that moves, along a vertical direction, inside the striking cylinder 30; a driver bit 2 that is mounted on the striking piston 30a; and a guide part 12c provided below the striking cylinder 30. The guide part 12c comprises a guide hole 12d through which the driver bit 2 passes, and an exhaust hole 12e through which the inside of the striking cylinder 30 is communicated with the outside of the screw driving machine 1A. The exhaust hole 12e is formed at a position separated outward from an inner peripheral surface of the guide hole 12d.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present disclosure relates to a driving tool for driving a fastener into a workpiece. [Background technology]

[0002] A driving tool is a tool that uses compressed air as a power source to operate a striking cylinder and move a driver axially to drive a fastener into a workpiece. A known example of such a driving tool is a screw driver that drives a screw, as an example of a fastener, into the workpiece and then tightens it (see, for example, Patent Document 1). Patent Document 1 also describes a nail driver that drives a nail, as an example of a fastener, into the workpiece.

[0003] In driving tools such as screw drivers and nail guns, when compressed air is supplied to the striking cylinder, the air pressure of the compressed air acts on the upper surface of the striking piston, causing the striking piston to move downward. As a result, in the driving tool, the air pressure of the compressed air supplied to the striking cylinder causes the striking piston to move the driver downward, driving the fastener into the material being driven. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-53745 Summary of the Invention [Problem to be solved by the invention]

[0005] When the striking piston moves downward, the air in the lower chamber of the striking cylinder formed below the striking piston is exhausted to the outside through gaps between the driver and the shaft hole through which the driver passes, the injection passage, etc. However, if the air in the lower chamber of the striking cylinder is not properly exhausted, the air pressure in the lower chamber of the striking cylinder increases, increasing the load on the striking piston as it moves downward and slowing down the speed at which the striking piston moves downward.

[0006] Furthermore, if the compressed air supplied from the blowback chamber (return air chamber) to the lower chamber of the striking cylinder does not properly exhaust the air inside the lower chamber of the striking cylinder when the striking piston returns to the top dead center position, the air pressure inside the blowback chamber and the lower chamber of the striking cylinder may increase. In this case, the speed at which the striking piston moves upward may become too high, causing it to hit the damper installed above the striking cylinder and bounce back, making it impossible for the striking piston to return to the top dead center position.

[0007] It is possible to increase the diameter of the shaft hole or injection passage through which the driver passes, allowing the air in the lower chamber of the striking cylinder to be exhausted to the outside through the gap between the outer periphery of the driver and the inner periphery of the shaft hole or injection passage. However, this configuration would increase the distance between the driver and the shaft hole or injection passage. Driving tools are configured so that the driver is guided by the shaft hole or injection passage as it moves. Therefore, if the distance between the driver and the shaft hole or injection passage is increased, it is not possible to prevent the driver from tilting when guided by the shaft hole or injection passage, and the driver's guiding ability by the shaft hole or injection passage is reduced.

[0008] Another option is to form a convex portion on the inner circumferential surface of the shaft hole or injection passage, allowing the air in the lower chamber of the striking cylinder to be exhausted to the outside. However, if the inner circumferential surface of the shaft hole or injection passage is uneven, it will be difficult to prevent the driver from tilting when it is guided by the shaft hole or injection passage, and the driver will not be guided well by the shaft hole or injection passage.

[0009] Therefore, in order to control the appropriate air sequence, it is necessary to maintain the air pressure in the striking cylinder at an appropriate level, and it is also necessary to ensure the driver's guiding ability.

[0010] The present disclosure has been made to solve such problems, and aims to provide a driving tool that is capable of maintaining an appropriate air pressure in the striking cylinder and ensuring the guiding ability of the driver. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the present disclosure provides a driving tool driven by the pneumatic pressure of compressed air, comprising: an impact cylinder to which compressed air is supplied; an impact piston that moves up and down inside the impact cylinder by the supplied compressed air; a driver that is attached to the impact piston and moves up and down; and a guide part provided on the underside of the impact cylinder, wherein the guide part has a guide hole through which the driver passes and an exhaust hole that connects the inside of the impact cylinder with the outside of the driving tool, and the exhaust hole is provided at a position spaced outward from the inner surface of the guide hole.

[0012] In this disclosure, when compressed air is supplied to the striking cylinder and the striking piston moves, the driver moves while being guided by the guide hole in the guide part. Also, by venting a portion of the air inside the striking cylinder to the outside through the exhaust hole, the air pressure above and below the striking piston inside the striking cylinder is maintained at an appropriate level. [Effects of the Invention]

[0013] In the present disclosure, in a driving tool operated by the pneumatic pressure of compressed air supplied to a striking cylinder, the air pressure in the striking cylinder can be maintained at an appropriate level for each operation. Also, by providing an exhaust hole at a position spaced outward from the inner circumferential surface of the guide hole, the function of guiding the driver by the guide hole is not hindered by the exhaust hole. [Brief explanation of the drawings]

[0014] [Figure 1A] 1 is a front cross-sectional view showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 1B] 1 is a side cross-sectional view showing an example of a screw driving machine according to an embodiment of the present invention. [Figure 1C]1 is an external perspective view showing an example of a screw driving machine according to an embodiment of the present invention; [Figure 2] 1 is a front cross-sectional view showing the main configuration of a screw driving machine according to an embodiment of the present invention. [Figure 3] 1 is an exploded perspective view showing a main configuration of a screw driving machine according to an embodiment of the present invention. FIG. [Figure 4A] 10A and 10B are front cross-sectional views showing examples of the operation of the screw driver according to the length of the screw. [Figure 4B] 10A and 10B are front cross-sectional views showing examples of the operation of the screw driver according to the length of the screw. [Figure 5A] 1 is a side cross-sectional view showing the configuration of a main part of a screw driving machine according to an embodiment of the present invention. [Figure 5B] 1 is a side cross-sectional view showing the configuration of a main part of a screw driving machine according to an embodiment of the present invention. [Figure 6] 1 is a plan cross-sectional view showing the configuration of a main part of a screw driving machine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a screw driver as an example of a driving tool of the present invention will be described with reference to the drawings.

[0016] <Configuration example of the screw driving machine according to this embodiment> Fig. 1A is a front cross-sectional view showing an example of a screw driving machine according to the present embodiment, Fig. 1B is a side cross-sectional view showing an example of a screw driving machine according to the present embodiment, Fig. 1C is an external perspective view showing an example of a screw driving machine according to the present embodiment, Fig. 2 is a front cross-sectional view showing the main configuration of the screw driving machine according to the present embodiment, and Fig. 3 is an exploded perspective view showing the main configuration of the screw driving machine according to the present embodiment.

[0017] The screw driver 1A uses the air pressure of compressed air to move a driver bit 2, which is an example of a driver, 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 202 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The nose portion 12 is an example of an injection path forming portion, and includes an injection passage 12a through which the screw 200 is supplied, an injection outlet 12b through which the screw 200 supplied to the injection passage 12a is injected, and a guide portion 12c that guides the driver bit 2.

[0022] 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 guide portion 12c has a guide hole 12d through which the driver bit 2 passes. The guide hole 12d is formed by providing an opening that penetrates the guide portion 12c at the upper end of the injection passage 12a in the extension direction. The guide hole 12d is provided in the movement path of the driver bit 2 and is an opening with a shape that allows the driver bit 2 to pass through. When the cross-sectional shape of the driver bit 2 is circular, the guide hole 12d is a circle with a diameter larger than the diameter of the driver bit 2 so as not to hinder the movement of the driver bit 2 in the vertical direction.

[0023] The screw driver 1A includes a striking cylinder 30 to which compressed air is supplied, a striking piston 30a that moves by the air pressure of the compressed air supplied to the striking cylinder 30, and a driver bit 2 that is attached to the striking piston 30a and moves in the axial direction.

[0024] 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.

[0025] The striking cylinder 30 is provided inside the main body 10 and is configured as a cylindrical space extending in the vertical direction.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In the screw driver 1A, when compressed air is supplied to the striking cylinder 30, the air pressure of the compressed air acts on the upper surface of the striking piston 30a, causing the striking piston 30a to move downward as indicated by arrow D. 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 arrow D, thereby driving the screw 200 into the workpiece. In addition, 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.

[0030] 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.

[0031] 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.

[0032] 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 from the space below the striking piston 30a to the guide part 12c. The second chamber 30d is an example of a striking cylinder upper chamber and is formed from the space above the striking piston 30a.

[0033] The striking cylinder 30 is provided with 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 guide portion 12c. The bumper 30e is annular and has a shape that allows the striking piston 30a to come into contact with it. The bumper 30e has a central opening that connects with the guide hole 12d, allowing the driver bit 2 to pass through the central opening. The striking piston 30a can move downward to a position where it comes into contact with the bumper 30e. The striking piston 30a and the driver bit 2 are at their bottom dead center positions when the striking piston 30a comes into contact with 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.

[0034] The screw driver 1A has an exhaust hole 12e in the guide portion 12c. The exhaust hole 12e is formed by providing an opening that penetrates the guide portion 12c on the outside of the guide hole 12d. The exhaust hole 12e is an opening that communicates with the outside of the screw driver 1A, which has the main body 10, the nose portion 12, etc., and is shaped to allow a predetermined amount of air to pass through. The exhaust hole 12e also communicates with an opening in the center of the bumper 30e. As a result, the first chamber 30c communicates with the outside of the screw driver 1A via the exhaust hole 12e.

[0035] The screws 200 supplied to the injection passage 12a are connected by the connecting band 201, and therefore the radial positions of the screws 200 in the injection passage 12a are approximately fixed. Therefore, the exhaust hole 12e is provided radially outward of the screw 200 with respect to the supply position Pp of the screw 200 supplied to the injection passage 12a. The supply position Pp has a radial range of the screw 200 that is approximately equal to the diameter of the head 202 of the screw 200. This prevents the air exhausted from the exhaust hole 12e from directly hitting the head 202 of the screw 200 positioned in the injection passage 12a. Note that the exhaust hole 12e may also be provided radially outward of the injection passage 12a. This configuration more reliably prevents the air exhausted from the exhaust hole 12e from directly hitting the head 202 of the screw 200 positioned in the injection passage 12a, regardless of variations in the type and position of the screw 200.

[0036] Furthermore, the exhaust hole 12e is not connected to the guide hole 12d. This prevents the formation of irregularities on the inner circumferential surface due to the guide hole 12d being connected to the exhaust hole 12e. The number of exhaust holes 12e may be one or more. In a configuration with multiple exhaust holes 12e, the cross-sectional areas and cross-sectional shapes of the exhaust holes 12e may be the same or different. Furthermore, the exhaust hole 12e may be circular or polygonal, such as triangular or rectangular. The exhaust hole 12e may also have an arc shape that follows the circumferential direction of the guide hole 12d. In this way, the shape and number of the exhaust holes 12e are not important as long as they are appropriately set according to the strength of the guide portion 12c and the exhaust flow rate from the exhaust hole 12e, can maintain the appropriate air pressure in the striking cylinder 30, and do not interfere with the driver guiding by the guide hole 12d.

[0037] In this example, the nose portion 12 is a separate component from the main body portion 10. When the nose portion 12 is attached to the main body portion 10, the lower end of the first chamber 30c of the striking cylinder 30 is closed by the guide portion 12c. The guide portion 12c may be integral with the main body portion 10 or with the striking cylinder 30.

[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 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 configured, for example, by 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 driving machine 1A is equipped with a contact unit 8 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 driving machine 1A also has 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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 the 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 by the second seal portion 30b2. Furthermore, when the striking piston 30a moves further downward and the second seal portion 30b2 passes through the side hole flow passage 32a, the timer chamber 32 is connected to the second chamber 30d via the side hole flow passage 32a. When the striking piston 30a is at the bottom dead center position, the timer chamber 32 is in a state where it is connected to the second chamber 30d via the side hole flow passage 32a.

[0049] 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.

[0050] The blowback chamber 33 is connected to the first chamber 30c via a side hole flow passage 33a depending on the position of the striking piston 30a, and is also connected to either the first chamber 30c or the second chamber 30d via a side hole flow passage 33b depending on the position of the striking piston 30a.

[0051] As a result, compressed air is supplied to the timer chamber 32 and the blowback chamber 33 from the striking cylinder 30 according to the position of the striking piston 30a as the striking piston 30a moves between the top dead center position and the bottom dead center position, and the pressure changes.

[0052] The contact portion 8 is supported so as to be movable in the up and down direction relative to the main body 10. The contact portion 8 has a contact top 80 attached to its lower end, which is brought into contact with the workpiece 300 to be driven.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 due to the balance of the loads generated by 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, and is at the bottom dead center position, blocking the air flow path 54 between the main valve lower chamber 53 and the striking cylinder 30. In contrast, when the main valve 5 is in operation, the main valve upper chamber 52 is connected to the atmosphere via the starting valve 6, and 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] In the starting valve 6, when the contact top 80 is pressed against the workpiece 300, the contact part 8 moves upward relative to the main body 10, and when the trigger 60 is pulled, the contact lever 60a comes into contact with the valve stem 62, causing the valve stem 62 to move upward. The starting valve 6 is activated when the valve stem 62 moves upward.

[0065] In contrast, in the starting valve 6, the contact lever 60a does not come into contact with the valve stem 62 simply by pressing the contact top 80 against the workpiece 300, causing the contact part 8 to move upward relative to the main body 10, or by pulling the trigger 60.

[0066] 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 portion 8. The order in which the operation of the trigger 60 and the operation of pressing the contact portion 8 are performed is arbitrary.

[0067] 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 and an on-off valve upper chamber 73b above the on-off valve 7. When compressed air is supplied to the on-off valve upper 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 on-off valve upper chamber 73b, the on-off valve 7 moves upward due to the pressure of the compressed air supplied to the on-off valve lower chamber 73a.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] The first control valve 72 is biased downward by the first biasing member 72b, and moves to the standby position P100. In addition, the first control valve 72 moves upward from the standby position P100, and moves to the operation end position via the pressure control start position.

[0073] 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.

[0074] 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.

[0075] In the control unit 70, the first control valve 72 and the second control valve 71 are configured as independent members. In the control unit 70, the first control valve 72 that has moved to the standby position P100 and the second control valve 71 that has moved to the standby position P110 are separated from each other to form a separation section 76. The separation section 76 is configured by providing a space between the upper end of the connecting section 72a, which is the upper end of the first control valve 72, and the lower end of the second control valve 71.

[0076] The screw feed unit 9 is operated by the air pressure of compressed air supplied from the blowback chamber 33 through the feed flow path 94, and engages the screw 200 connected by the connecting band 201 with a claw portion (not shown) and sends it to the injection passage 12a.

[0077] The magazine 90 is provided below the handle portion 11 and connected to the nose portion 12. The magazine 90 stores a screw connector in the form of, for example, a spiral wound screw body, in which a plurality of screws 200 are connected by connecting bands 201. The magazine 90 is provided with a lid portion 91 that can be opened and closed.

[0078] 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 portion 8. When pressed by the contact portion 8, the drive depth adjustment unit 86 activates the first control valve 72.

[0079] The tightening depth adjustment part 86 is supported so as to be movable up and down along the movement direction of the contact part 8. The tightening depth adjustment part 86 is biased downward by a biasing member 86c such as a coil spring. The tightening depth adjustment part 86 is also configured so that the overall length along the up and down direction can be adjusted by operating a dial part 86d.

[0080] The contact portion 8 has an abutment portion 81 that comes into contact with the tightening depth adjustment portion 86. In the contact portion 8, the portion where the contact top 80 is attached and the portion where the abutment portion 81 is provided are connected so as to be able to move up and down in unison.

[0081] When the contact portion 8 is at the bottom dead center position, the tightening depth adjustment portion 86 is separated from the abutment portion 81. When the contact portion 8 moves upward from the bottom dead center position, the abutment portion 81 comes into contact with the tightening depth adjustment portion 86.

[0082] Furthermore, before being pushed and moved by the contact portion 8, the tightening depth adjustment portion 86 is separated from the first control valve 72. When the contact portion 8 moves upward from the bottom dead center position, the abutment portion 81 of the tightening depth adjustment portion 86 comes into contact with the first control valve 72. When the tightening depth adjustment portion 86 is pushed and moved upward by the contact portion 8, it comes into contact with the first control valve 72.

[0083] The tightening depth adjusting portion 86 is pushed up by the contact portion 8 moving upward, and when it moves to a position where it contacts the movement restricting portion 86e, it restricts the contact portion 8 from moving further upward.

[0084] As a result, the position of the contact part 8 restricted by the movement of the tightening depth adjusting part 86 to the position where it contacts the movement restricting part 86e becomes the upper support point position of the contact part 8.

[0085] Furthermore, by changing the overall length of the screwing depth adjustment portion 86, the position at which the contact portion 81 abuts moves up and down. This moves the top dead center position of the contact portion 8. When the top dead center position of the contact portion 8 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.

[0086] In addition, the screw driver 1A may not be equipped with the tightening depth adjustment unit 86, and the contact unit 8 may be in direct contact with the first control valve 72, thereby operating the first control valve 72 and determining the upper fulcrum position of the contact unit 8.

[0087] <Example of operation of the screw driving machine according to this embodiment> Next, an example of the operation of the screw driver 1A that drives and tightens the screw 200 will be described.

[0088] The operator holds the handle portion 11 of the screw driving machine 1A and presses the contact top 80 against the workpiece 300. When the contact top 80 of the screw driving machine 1A is pressed against the workpiece 300, the contact portion 8 moves upward relative to the main body portion 10 due to the relative movement between the contact portion 8 and the main body portion 10.

[0089] When the contact part 8 moves upward relative to the main body 10, it becomes possible to sign in. When the trigger 60 is pulled in this state, the contact lever 60a presses the valve stem 62 of the starting valve 6, and the starting valve 6 enters a sign-in state in which it can be operated.

[0090] 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.

[0091] 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, 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, and drives the screw 200 supplied from the magazine 90 to the injection passage 12a into the workpiece 300.

[0092] 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 flow passage 33b of the striking cylinder 30, compressed air is supplied from the second chamber 30d through the side hole flow passage 33b to the blowback chamber 33, and the pressure in the blowback chamber 33 increases.

[0093] 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.

[0094] 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.

[0095] When the contact portion 8 has moved to the bottom dead center position, the control portion 70 does not allow the tightening depth adjustment portion 86 to come into contact with the first control valve 72. When the tightening depth adjustment portion 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 a standby position P100, and the second control valve 71 is urged by the second urging member 71a to move to a standby position P110.

[0096] When the contact top 80 is pressed against the workpiece 300, the main body 10 moves further downward following the tightening of the screw 200, and the contact part 8 moves relatively upward, the abutment part 81 comes into contact with the tightening depth adjustment part 86 and pushes the tightening depth adjustment part 86 upward.

[0097] The tightening depth adjustment portion 86 is pushed up by the contact portion 8 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 contact portion 8 is restricted. When the tightening depth adjustment portion 86 moves to a position where it contacts the movement restricting portion 86e and the contact portion 8 moves to the top dead center position, the contact portion 8 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.

[0098] 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 until the first control valve 72 moves to the pressure control start position, the third chamber 75a is maintained at atmospheric pressure, and the first control valve 72 does not operate with air pressure.

[0099] 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.

[0100] 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.

[0101] When compressed air is supplied to the on-off valve upper chamber 73b, the on-off valve 7 moves downward due to the difference between the pressure acting on the on-off valve 7 by the compressed air supplied to the on-off valve upper chamber 73b and the load 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.

[0102] When the rotation of the driver bit 2 stops and the screw 200 has been tightened, the worker reduces the force pressing the contact top 80 against the workpiece 300 and moves the main body 10 in a direction away from the workpiece 300.

[0103] When the main body 10 moves in a direction away from the workpiece 300, the main body 10 and the contact part 8 move relative to each other, causing the contact part 8 to move downward. When the contact part 8 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.

[0104] 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.

[0105] As described above, a screw driver is a driving tool that uses compressed air as a power source to operate an impact cylinder, moves a driver axially to drive a screw into the workpiece, and then uses compressed air as a power source to operate an air motor, rotates the driver, and tightens the screw into the workpiece.

[0106] In such screw drivers, an automatic stop control mechanism has been known that automatically stops the air motor when the screw is tightened by the air motor and the screw is driven to a predetermined depth, thereby controlling the screw-driving depth to be constant.

[0107] The automatic stop control mechanism for the air motor includes a control section having a valve that operates with compressed air supplied via the striking cylinder, and a flow path through which the compressed air supplied to the control section via the striking cylinder passes, with an opening connected to this flow path formed at a predetermined position on the striking cylinder.The automatic stop control mechanism for the air motor is configured so that the valve operates when the position of the contact section pressed against the workpiece and the position of the striking piston each reach a predetermined position.

[0108] Conventionally, in screw drivers, the depth to which a screw is driven is generally constant regardless of the length of the screw used. Therefore, the position of the striking piston immediately after the screw is driven into the workpiece may differ depending on the length of the screw.

[0109] However, depending on the position of the striking piston immediately after driving the screw into the workpiece, the balance of air pressure inside the striking cylinder could change, and before the striking piston reached the specified position, the air pressure inside the lower chamber of the striking cylinder could rise, causing the air motor to stop.

[0110] Furthermore, if the air in the lower chamber of the striking cylinder is not properly exhausted when the striking piston moves downward, the air pressure in the lower chamber of the striking cylinder increases, increasing the load on the striking piston as it moves downward and reducing the speed at which the striking piston moves downward.

[0111] Furthermore, if the compressed air supplied from the blowback chamber to the lower chamber of the striking cylinder does not properly exhaust the air in the lower chamber when the striking piston returns to the top dead center position, the air pressure in the blowback chamber and the lower chamber of the striking cylinder may become excessively high relative to the air pressure in the upper chamber of the striking cylinder. In this case, the striking piston may move upward too quickly, collide with the damper provided above the striking cylinder, and bounce back, preventing the striking piston from returning to the top dead center position.

[0112] It is possible to increase the diameter of the guide hole through which the driver passes, allowing the air in the lower chamber of the striking cylinder to be exhausted to the outside through the gap between the outer periphery of the driver and the inner periphery of the guide hole. However, in a configuration in which the gap between the outer periphery of the driver and the inner periphery of the guide hole is used as an exhaust hole, the distance between the driver and the guide hole becomes wider, making it difficult to prevent the driver from tilting when guided by the guide hole, and reducing the guide ability of the guide hole to guide the driver.

[0113] Another option is to form a convex portion on the inner circumferential surface of the guide hole, creating an exhaust hole that connects to the guide hole and allows air in the lower chamber of the striking cylinder to be exhausted to the outside. However, if the exhaust hole is connected to the guide hole, unevenness will be formed on the inner circumferential surface of the guide hole. If unevenness is formed on the inner circumferential surface of the guide hole, it will be difficult to prevent the driver from tilting when guided by the guide hole, and the guide hole will not be able to guide the driver.

[0114] Therefore, in order to achieve the proper air sequence in a screw driver, it is necessary to maintain the appropriate air pressure in the striking cylinder. It is also necessary to ensure the driver's guiding ability. Details are explained below.

[0115] 4A and 4B are front cross-sectional views showing examples of the operation of the screw driver according to the length of the screw. Fig. 4A shows the state immediately after a screw 200a of a first length L1 has been driven into a workpiece 300, and Fig. 4B shows the state immediately after a screw 200a of a second length L2, which is longer than the first length L1, has been driven into the workpiece 300.

[0116] As described above, when the contact portion 8 moves to the top dead center position, the contact portion 8 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 P101.

[0117] Immediately after the screw 200a of the first length L1 is driven into the workpiece 300, the striking piston 30a is positioned so that the side hole flow passage 32a is between the first seal portion 30b1 and the second seal portion 30b2. When the striking piston 30a moves to the bottom dead center position, the second seal portion 30b2 passes through the side hole flow passage 32a.

[0118] As a result, even if the first control valve 72 moves to the pressure control start position P101 and the air flow path to the outside through the exhaust path 75d is blocked, the pressure in the timer chamber 32 does not increase until the striking piston 30a moves to the bottom dead center position. Therefore, the pressure in the control valve cylinder 75 does not increase, and the first control valve 72 is prevented from moving further upward from the pressure control start position P101.

[0119] Therefore, compressed air continues to be supplied to the air motor 31 until the striking piston 30a moves to the bottom dead center position, and the screw 200a is fastened into the workpiece 300.

[0120] In contrast, the driving depth of the screw 200b with the second length L2 into the workpiece 300 is approximately the same as that of the screw 200a with the first length L1. Therefore, immediately after the screw 200b with the second length L2 is driven into the workpiece 300, the striking piston 30a does not pass through the side hole flow path 32a, and the first seal portion 30b1 is located above the side hole flow path 32a.

[0121] Immediately after the screw 200b of the second length L2 is driven into the workpiece 300, the striking piston 30a passes through the side hole flow passage 33b, and the second seal portion 30b2 is located below the side hole flow passage 33b.

[0122] As a result, compressed air is supplied from the second chamber 30d through the side hole flow path 33b to the blowback chamber 33. If the air in the first chamber 30c cannot be properly exhausted to the outside, the compressed air in the blowback chamber 33 flows into the timer chamber 32 through the side hole flow path 33a, the first chamber 30c, and the side hole flow path 32a, causing the pressure in the timer chamber 32 to rise.

[0123] When the first control valve 72 moves to the pressure control start position P101 and the air flow path to the outside through the exhaust path 75d is blocked, if the pressure in the timer chamber 32 rises, the pressure in the control valve cylinder 75 will rise, and the first control valve 72 may move further upward from the pressure control start position P101. This may cause the supply of compressed air to the air motor 31 to stop before the head 202 of the screw 200b is tightened to the point where it is flush with the workpiece 300.

[0124] Therefore, the screw driver 1A includes an exhaust hole 12e in the guide portion 12c. The exhaust hole 12e connects the first chamber 30c to the outside of the screw driver 1A. This allows the air in the first chamber 30c to be properly exhausted to the outside of the screw driver 1A. Therefore, even if compressed air is supplied from the second chamber 30d to the blowback chamber 33 through the side hole flow path 33b and then from the blowback chamber 33 to the first chamber 30c through the side hole flow path 33a, the air in the first chamber 30c is exhausted to the outside, and the pressure in the timer chamber 32 does not increase. Therefore, the pressure in the control valve cylinder 75 does not increase, and the first control valve 72 is prevented from moving further upward from the pressure control start position P101.

[0125] Therefore, compressed air continues to be supplied to the air motor 31 until the striking piston 30a moves to the bottom dead center position, and the screw 200b is fastened into the workpiece 300. When the striking piston 30a moves to the bottom dead center position, the bottom surface of the striking piston 30a and the top surface of the bumper 30e seal the side hole flow path 33a and the space inside the bumper 30e, so that the compressed air in the blowback chamber 33 is prevented from flowing from the side hole flow path 33a into the space inside the bumper 30e, and the air in the blowback chamber 33 does not flow out through the exhaust hole 12e to the outside.

[0126] Furthermore, the exhaust hole 12e is provided radially outward of the screw 200 with respect to the injection passage 12a. This prevents the air exhausted from the exhaust hole 12e from directly hitting the head 202 of the screw 200 located in the injection passage 12a. This prevents the screw 200 located in the injection passage 12a from coming off the connecting belt 201 and falling off.

[0127] Furthermore, the guide hole 12d is not connected to the exhaust hole 12e, which prevents the exhaust hole 12e from forming irregularities on the inner peripheral surface. As a result, the exhaust hole 12e does not interfere with the guide hole 12d's ability to guide the upward and downward movement and rotation of the driver bit 2. Furthermore, when the driver bit 2 is guided by the guide hole 12d, the inclination of the driver bit 2 is kept small, ensuring that the guide hole 12d can guide the driver bit 2.

[0128] In the above embodiment, the screw driver 1A has been described as an example of a driving tool, but the present invention may also be applied to a nail driver. A nail driver is a driving tool that uses compressed air as a power source to operate a striking cylinder and move a driver in the axial direction to drive a nail into a workpiece.

[0129] When compressed air is supplied to the striking cylinder of a nail gun, the air pressure of the compressed air acts on the upper surface of the striking piston, causing the striking piston to move downward. As a result, in the nail gun, the air pressure of the compressed air supplied to the striking cylinder causes the striking piston to move the driver downward, driving the nail into the material to be driven.

[0130] At this time, the air in the lower chamber of the striking cylinder formed below the striking piston is exhausted to the outside through the gap between the driver and the guide hole through which the driver passes. However, even in a nail gun, if the air in the lower chamber of the striking cylinder is not properly exhausted, the air pressure in the lower chamber of the striking cylinder increases, increasing the load on the striking piston as it moves downward and slowing down the speed at which the striking piston moves downward.

[0131] Furthermore, if the air in the lower chamber of the striking cylinder is not properly exhausted due to the pressure of the compressed air supplied from the blowback chamber to the lower chamber of the striking cylinder when the striking piston returns to the top dead center position, the air pressure in the blowback chamber and the lower chamber of the striking cylinder may increase. In this case, even in a nail gun, the speed at which the striking piston moves upward may become too high, causing the striking piston to bounce off after hitting the damper provided above the striking cylinder, preventing the striking piston from returning to the top dead center position.

[0132] Therefore, a nail gun also has an exhaust hole in the guide section having a guide hole for guiding the driver. The exhaust hole connects the lower chamber of the striking cylinder with the outside of the nail gun. This allows the air in the lower chamber of the striking cylinder to be properly exhausted to the outside of the nail gun. This prevents a decrease in the speed of the striking piston moving downward during the nail driving operation. Furthermore, the speed of the striking piston moving upward can be adjusted to an appropriate speed when the striking piston returns to the top dead center position.

[0133] In addition, in nail guns, the air in the lower chamber of the striking cylinder can be exhausted to the outside by providing an exhaust hole that is connected to the guide hole. However, when the exhaust hole is provided in a manner that connects to the guide hole, unevenness is formed on the inner peripheral surface of the guide hole. If unevenness is formed on the inner peripheral surface of the guide hole, it is not possible to prevent the driver from tilting when guided by the guide hole, and the guide hole's ability to guide the driver is reduced.

[0134] Another possible configuration is to increase the diameter of the guide hole and use the gap between the outer periphery of the driver and the inner periphery of the guide hole as an exhaust hole. However, in this configuration, the gap between the driver and the guide hole becomes wider, so it is still not possible to prevent the driver from tilting when it is guided by the guide hole, and the guide hole's ability to guide the driver is reduced.

[0135] In contrast, in nail guns, by providing exhaust holes outside the guide holes through which the driver passes, the exhaust holes are not connected to the guide holes, and unevenness on the inner peripheral surface of the guide holes is suppressed. As a result, the exhaust holes do not interfere with the vertical movement and rotation of the driver. Furthermore, when the driver is guided by the guide holes, the inclination of the driver is kept small, ensuring the driver's guiding ability by the guide holes.

[0136] <Configuration example to assist driver replacement> 5A and 5B are side cross-sectional views showing the configuration of the main parts of the screw driving machine of this embodiment related to the configuration that assists in replacing the driver, and FIG. 6 is a plan cross-sectional view showing the configuration of the main parts of the screw driving machine of this embodiment.

[0137] The screw driver 1A includes a rotation restricting unit 105 that restricts and releases the rotation of a rotor 31b1, which is an example of a rotating member, and a rotation stopper 106 that restricts the rotation of the rotation restricting unit 105. The rotation restricting unit 105 includes an operating unit 105a that can be operated from outside the main body 10, and a rotation restricting member 105b that engages with the rotor 31b1.

[0138] The main body 10 is provided with a cover 10a that covers the air motor 31. A rotation restricting unit 105 is attached to the upper surface of the cover 10a of the main body 10. The rotation restricting unit 105 is attached so as to be movable up and down relative to the cover 10a. Furthermore, the upper surface of the operation unit 105a of the rotation restricting unit 105 is exposed on the upper surface of the cover 10a.

[0139] The rotation restricting member 105b is configured by providing a convex portion that protrudes downward at the lower end of the rotation restricting portion 105.

[0140] The rotation stopper 106 is configured by providing a convex portion that comes into contact with the rotation restrictor 105 on the inner surface of the cover 10a.

[0141] The rotor 31b1 has an engaged portion 31b4 that engages with the rotation restricting member 105b. The engaged portion 31b4 is configured by providing a groove that engages with the rotation restricting member 105b at the upper end of the rotor 31b1.

[0142] When compressed air is supplied to the air motor 31, the rotation restricting portion 105 is pushed upward by the air pressure of the compressed air that flows from the air motor 31 into the inside of the cover portion 10a, and moves to the standby position. When the rotation restricting portion 105 is in the standby position, as shown in Fig. 5A, the rotation restricting member 105b is separated from and does not engage with the engaged portion 31b4. This releases the restriction on the rotation of the rotor 31b1 by the rotation restricting portion 105, and the rotor 31b1 becomes rotatable.

[0143] When replacing the driver bit 2, in a non-driven state where compressed air is not supplied to the air motor 31, etc., the operating portion 105a is pressed downward to move the rotation restricting portion 105 downward. When the rotation restricting portion 105 moves downward, the rotation restricting member 105b engages with the engaged portion 31b4, as shown in FIG. 5B.

[0144] The rotation restricting portion 105 is in contact with the rotation stopping portion 106, and is therefore unable to rotate relative to the main body portion 10. As a result, when the rotation restricting member 105b engages with the engaged portion 31b4, the rotation of the rotor 31b1 is restricted. As the rotation of the rotor 31b1 is restricted, the rotation of the motor shaft 31a connected to the rotor 31b1 is restricted.

[0145] The driver bit 2 is fixed to the motor shaft 31a by fastening a male thread (not shown) to a female thread (not shown) formed on the motor shaft 31a.

[0146] Therefore, a tool (not shown) is inserted through the injection passage 12a, and the tool (not shown) is engaged with the driver bit 2 exposed in the guide hole 12d, and the driver bit 2 is rotated in the direction to loosen the screw, thereby removing the driver bit 2 from the motor shaft 31a.

[0147] When the striking piston 30a is at the top dead center position, the lower end of the driver bit 2 is in the guide hole 12d. As a result, when the driver bit 2 is removed, the driver bit 2 is guided by the guide hole 12d and can be taken out without remaining inside the striking cylinder 30.

[0148] After removing the driver bit 2 to be replaced, a new driver bit 2 can be attached to the motor shaft 31a by inserting it into the striking cylinder 30 through the guide hole 12d and rotating the driver bit 2 in the screw-tightening direction with a tool (not shown). When the rotation restricting member 105b engages with the engaged portion 31b4 by pushing the rotation restricting portion 105 downward, the rotation of the rotor 31b1 and the motor shaft 31a can be restricted without using a tool to hold the rotation restricting portion 105. The rotation restricting portion 105 is pushed upward by the air pressure of the compressed air flowing from the air motor 31 into the cover portion 10a, and moves to the standby position. This eliminates the need for any tools or operations to return the rotation restricting portion 105 to the standby position.

[0149] Furthermore, in the screw driver 1A, the exhaust hole 12e is not connected to the guide hole 12d, which prevents the formation of irregularities on the inner circumferential surface of the guide hole 12d. As a result, when the driver bit 2 removed from the motor shaft 31a is guided alone in the guide hole 12d, the tilt of the driver bit 2 is kept small, ensuring the guiding ability of the driver bit 2 by the guide hole 12d. Even if the driver bit 2 removed from the motor shaft 31a tilts, the driver bit 2 does not come into contact with the inside of the striking cylinder 30 because it is guided by the guide hole 12d. Furthermore, when a new driver bit 2 is inserted into the striking cylinder 30 through the guide hole 12d, the position of the male thread (not shown) of the driver bit 2 is easily aligned with the female thread (not shown) formed on the motor shaft 31a, thanks to the guide of the driver bit 2 by the guide hole 12d. [Explanation of symbols]

[0150] 1A...Screw driver, 10...Main body, 10a...Cover, 11...Handle, 12...Nose (injection path forming part), 12a...Injection passage, 12b...Injection outlet, 12c...Guide, 12d...Guide hole, 12e...Exhaust hole, 13...Main chamber, 14...Exhaust pipe, 2...Driver bit, 30...Striking cylinder, 30a...Striking piston, 31...Air motor, 31a...Motor shaft, 31d...Reduction gear, 32...Timer chamber, 32a... Side hole flow passage, 33...blowback chamber, 33a, 33b...side hole flow passage, 5...main valve, 6...starting valve, 60...trigger, 7...on-off valve, 70...control section, 8...contact section, 80...contact top, 81...abutment section, 9...screw feed section, 90...magazine, 105...rotation restriction section, 105a...operation section, 105b...rotation restriction member, 106...rotation stop section, 200, 200a, 200b...screw, 201...connecting belt, 300...workpiece to be driven

Claims

1. A driving tool driven by compressed air pressure, a striking cylinder supplied with compressed air; a striking piston that moves up and down inside the striking cylinder by the supplied compressed air; a driver attached to the striking piston and moving up and down; a guide portion provided below the striking cylinder, the guide portion has a guide hole through which the driver passes and an exhaust hole that communicates the inside of the striking cylinder with the outside of the driving tool, The exhaust hole is provided at a position spaced outward from the inner circumferential surface of the guide hole. Driving tool.

2. an injection passage forming section having an injection passage through which the fastener is supplied; the injection passage forming portion is provided below the guide portion, The exhaust hole is provided radially outward of the fastener relative to a supply position of the fastener supplied to the injection passage. The driving tool according to claim 1 .

3. an injection passage forming section having an injection passage through which the fastener is supplied; the injection passage forming portion is provided below the guide portion, The exhaust hole is provided radially outside the injection passage. The driving tool according to claim 1 .

4. The guide portion has a plurality of the exhaust holes. The driving tool according to claim 2 .

5. The striking cylinder has a first chamber formed below the striking piston, The guide portion is provided below the first chamber and connects the first chamber to the outside of the driving tool. The driving tool according to claim 1 .

6. a rotating member that supports the driver rotatably around an axis; A rotation restricting portion is provided for restricting and releasing the rotation of the rotary member. The driving tool according to claim 1 .

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