JP3622512B2 - Automatic stopping device for screwing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic stop device for a screw driving machine, and more particularly to an automatic stop device for a screw driving machine that automatically stops an air motor when screwing is completed.
[0002]
[Prior art]
There is known a screw driving machine having a structure in which a high-pressure air is used as a power source and a driver bit connected to a piston of a pneumatic cylinder is rotationally driven by an air motor. As a safety device, the screw driving machine is provided with a contact arm that protrudes from the nose of the screw driving machine in the screw driving direction by the bias of the spring, and the tip of the contact arm is placed on the surface of the screw driving object. When the other end of the contact arm is pressed against the contact arm stopper in the screw driving machine, the trigger lever can be operated.
[0003]
When the trigger lever is actuated, the piston in the cylinder rapidly descends, and the driver bit connected to the piston drives the screw into the building material to some extent. At the same time, the contact arm is unlocked by the contact arm stopper, and the air motor turns the driver bit. Is driven to rotate the screw. Then, when the operation of the trigger lever is released, the air motor stops, the piston and the driver bit rise and return to the standby position.
[0004]
There is also known a configuration in which when the screwing is completed, the air motor is automatically stopped and the screwing depth is controlled to be constant. As an automatic stop device, there is an automatic stop device in which an open / close valve is provided in an air supply line to an air motor and the air motor is automatically stopped by switching the open / close valve by a contact arm.
[0005]
When the screw is driven to rotate by the air motor and enters the screwing object, the distance between the screwing machine and the screwing object decreases, and the contact arm is further pushed into the screwing machine body side. In the automatic stop device, when the screwing is completed, the contact arm pushes the stem of the on-off valve, the on-off valve is switched to the pressure air shut-off position, and the air motor stops.
[0006]
As another type, when the piston connected with the driver bit reaches the bottom dead center with screwing, the seal member attached to the piston shuts off the air supply path to the air motor and stops the air motor. It has been known.
[0007]
[Problems to be solved by the invention]
When the screwing operation is performed using the screw driving machine, it is necessary that the contact arm of the screw driving machine is pressed against the object to be screwed with a certain amount of pressure so that the screwdriver can reliably rotate the screw. However, if this pressing load is excessive, the driver bit and the piston are pushed into the screwdriver main body before the screwing is completed, and the contact arm is also pushed accordingly. In a screw driving machine of the type in which the on / off valve is switched by the contact arm, such a state occurs that the on / off valve is switched by being pushed by the contact arm and the air motor is stopped before the screwing is completed.
[0008]
In addition, when the load for pressing the screw driving machine against the object to be screwed is insufficient, the screw driving machine may be separated from the surface of the screw driving object by a reaction force at the time of screw driving. In the screw driving machine of the type in which the air supply path to the air motor is shut off when the piston reaches bottom dead center, the piston reaches bottom dead center before screwing is completed and the air motor It will stop.
[0009]
[Means for Solving the Problems]
The present invention is proposed in order to achieve the above object, and a driver bit in which a bit engaging with a screw head is formed at the tip of a spline shaft is rotatably coupled to a piston of a pneumatic cylinder, and a spline groove center is provided. A driver bit is inserted into the gear with the hole formed, and an air motor is provided to rotate the driver bit through the gear. The piston of the pneumatic cylinder is driven to drive a screw with the driver bit, and the driver bit is driven to rotate with the air motor. A screw driving machine for screwing the screws,
An open / close valve is provided in the air supply path to the air motor, a contact arm that is slidable along the nose part of the screw driving machine is provided, and the contact arm is urged in the direction of screw injection by a spring to tip the tip of the contact arm. also projecting from the part, a stem for opening and closing operation of the vent port of the pilot air chamber of the on-off valve is opposed to the other end of the contact arm, the contact arm is the stem to be pushed into the screw gun body with the progress of screwing opening the vent port by pressing an automatic stop device of the configuration the screw driving machine as the on-off valve to stop the air motor by close,
A sub-open / close valve is installed in parallel with the open / close valve, and the spool in the valve sleeve portion of the sub-open / close valve is urged downward by a spring so that the inlet port of the sub-open / close valve and the vent port provided above it The pilot port provided at the lower part of the auxiliary on-off valve is connected to the outlet port provided at the lower end of the pneumatic cylinder, and the piston of the pneumatic cylinder is further connected to the bottom dead center. when reaching the outlet port pressure air in the air pressure cylinder is discharged is provided on the tip vicinity of the air pressure cylinder, and connect the outlet port to the pilot port of the auxiliary switching valve, the piston bottom dead center portion It reached the auxiliary switching valve is open, and, when the contact arm is pressed stem of the on-off valve, pressure air in the pilot air chamber of the on-off valve is evacuated through the sub-off valve, Closing closes the air motor is intended to provide an automatic stop device configured screw gun to stop.
[0010]
[Means for Solving the Problems]
The present invention is proposed to achieve the above object, and a driver bit having a bit engaged with a screw head formed at the tip of a spline shaft is rotatably coupled to a piston of a pneumatic cylinder, and has a spline groove. A driver bit is inserted into the gear with the center hole formed, and an air motor that rotates the driver bit through the gear is provided. The piston of the pneumatic cylinder is driven and a screw is driven by the driver bit, and the driver bit is rotated by the air motor. A screw driving machine for screwing the screw,
An open / close valve is provided in the air supply path to the air motor, and a contact arm that is slidable along the nose part of the screwing machine is projected from the tip of the nose part. In the automatic stopping device of the screw driving machine configured to stop the air motor by closing the on-off valve by the upward movement of the contact arm to be pushed,
The pneumatic cylinder is provided with an air passage through which pressurized air acting on the back of the piston is supplied to the on-off valve when the piston reaches near the bottom dead center, and from the pneumatic cylinder when the piston reaches near the bottom dead center. An automatic stop device for a screw driving machine is provided, wherein a cooperative mechanism for closing the on-off valve is formed by a cooperative action of an air pressure supplied to the on-off valve and an upward movement of a contact arm.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a screw driving machine 1, in which a pneumatic cylinder 3 and an air motor 4 are housed in a housing 2, and a trigger valve 7 in the grip portion 5 is disposed by a trigger lever 6 disposed in front of the grip portion 5 of the housing 2. Open and close. The inside of the grip part 5 is an air chamber 8, and an air hose is connected to an air hose connector 9 attached to the bottom of the grip part 5 to supply pressurized air from the air compressor to the air chamber 8.
[0012]
A spline groove is formed on the outer peripheral surface of the driver bit 11 connected to the piston 10 of the pneumatic cylinder 3, and the driver bit 11 is inserted into a hole with a spline groove at the center of the gear 12 mounted in the front portion of the housing 2. The piston 10 and the driver bit 11 are slidable with respect to the gear 12. The power of the air motor 4 that rotationally drives the driver bit 11 is transmitted to the final stage gear 12 through a plurality of reduction gears 13 arranged at the front portion of the housing 2.
[0013]
The screw feeding device 15 provided on the side surface of the nose portion 14 is composed of a pneumatic cylinder and a ratchet type feeding claw that are not shown in the figure as in a general air nailing machine. Supply to the inside of the nose part 14.
[0014]
A swingable free arm 17 is attached to the trigger lever 6, and a contact arm 18 facing the front surface of the free arm 17 extends forward through the back side of the pneumatic cylinder 3 in FIG. Projecting from the portion 14 in the screw injection direction. An openable / closable chuck 20 is pivotally attached to a screw guide 19 at a front end portion of the contact arm 18 that can slide back and forth, and the chuck 20 is closed by a spring (not shown).
[0015]
By pushing the screw guide 19 against the building material and pushing the contact arm 18, the contact arm 18 contacts the tip of the free arm 17. When the trigger lever 6 is rotated in this state, the trigger valve is connected via the free arm 17. 7 is pushed, the trigger valve 7 is switched, and a known misfiring prevention mechanism is constructed in which the pneumatic cylinder 3 and the air motor 4 are not activated when only the trigger lever 6 is operated.
[0016]
An automatic stop device 21 comprising two on-off valves for opening and closing the air supply path to the air motor 4 is built in the side surface of the housing 2 shown in FIG. 2 (the back surface of the pneumatic cylinder 3 in FIG. 1). Yes.
[0017]
Next, the automatic stop device 21 will be described with reference to FIGS. 3 to 6, the right side from the center line is a vertical section of the screw driving machine as in FIG. 1, and the left side from the center line is a horizontal section.
[0018]
FIG. 3 shows the automatic stop device 21 in a standby state. The on-off valve 22 of the automatic stop device 21 includes a cylindrical main spool 24 inserted into the valve sleeve portion 23 and a small diameter inserted below the main spool 24. An O-ring 26 is mounted on each of the main spool 24 and the land of the pilot spool 25.
[0019]
The main spool 24 is in the raised position by the urging force of the compression spring 27, and is in a position where the inlet port 28 and the outlet port 29 at the upper part of the valve sleeve portion 23 are always in communication as shown in FIG. The pilot spool 25 is urged downward by a compression spring 30 inserted into the main spool 24 to close the lower vent port 31 of the valve sleeve portion 23. The lower end portion of the pilot spool 25 protrudes downward through the center hole of the valve sleeve portion 23 and faces the stem 33 attached to the center hole of the adjustment dial 32 attached to the lower end portion of the valve sleeve portion 23. The tip of the branching portion that branches in parallel from the middle of the contact arm 18 faces the lower surface of the stem 33.
[0020]
The inlet port 28 of the on-off valve 22 is connected to the head side air chamber 3 a on the back surface of the piston 10 of the pneumatic cylinder 3, the outlet port 29 is connected to the air motor 4, and the lower pilot port 34 is connected to the air chamber 8. doing. The main spool 24 is formed with a passage 24 a penetrating into the inner space of the main spool 24 at a position corresponding to the pilot port 34, and the pressure air in the air chamber 8 passes through the inside of the main spool 24 to the bottom surface of the main spool 24. It is supplied to the pilot air chamber 23a.
[0021]
The spool 37 in the valve sleeve portion 36 of the auxiliary on-off valve 35 arranged in parallel with the on-off valve 22 is urged downward by a compression spring 38 to always shut off the inlet port 39 and the vent port 40 above it. . The pilot port 41 below the auxiliary opening / closing valve 35 is connected to an outlet port 3b provided in the vicinity of the lower end of the pneumatic cylinder 3, and when the piston 10 reaches the bottom dead center, the pressure air in the pneumatic cylinder 3 is auxiliary opened / closed. Supplied to the pilot port 41 of the valve 35. The vent port 31 of the on-off valve 22 is connected to the inlet port 39 of the sub on-off valve 35. When the sub on-off valve 35 is opened, the vent port 31 of the on-off valve 22 communicates with the atmosphere.
[0022]
Next, the operation of the screw driving machine will be described. The tip of the screw guide 19 shown in FIG. 1 is pressed against the surface of the object to be screwed in. The contact arm 18 is pushed in until it abuts against a contact arm stopper (not shown). When the trigger lever 6 is activated, the trigger valve 7 is opened. 3, the pressure air in the pilot air chamber 43 acting on the outer edge portion of the upper surface of the head valve 42 of the pneumatic cylinder 3 shown in FIG. 3 is discharged to the atmosphere, and the head valve 42 rises in FIG. As a result, pressurized air flows into the pneumatic cylinder 3 from the air chamber 8 on the outer periphery of the pneumatic cylinder 3, the piston 10 and the driver bit 11 are lowered to strike the screw in the nose portion 14, and the air motor 4 is driven by the driver bit 11. , And the piston 10 moves to the vicinity of the bottom dead center.
[0023]
When the screw is driven into the object to be screwed, the lock of the contact arm 18 by the contact arm stopper is released, and the screw is further screwed by the air motor 4. As the screw is screwed, the piston 10 moves toward the bottom dead center, the screwing machine approaches the screwing object, and the contact arm 18 is further pushed into the screwing machine body.
[0024]
When the piston 10 passes through the outlet port 3b of the pneumatic cylinder 3 and reaches the bottom dead center, the high-pressure air in the pneumatic cylinder 3 is supplied to the pilot port 41 of the auxiliary opening / closing valve 35 through the outlet port 3b. As shown in FIG. 4, the sub open / close valve 35 is opened, and when the screwing is completed, the contact arm 18 pushes up the stem 33 and slides the pilot spool 25 of the open / close valve 22 upward.
[0025]
When the pilot spool 25 moves upward, the pilot air chamber 23a and the vent port 31 on the lower surface of the main spool 24 are opened, and the pilot port 34 and the pilot air chamber 23a are shut off and act on the lower surface of the main spool 24. The pilot pressure is exhausted from the vent port 31 to the atmosphere through the sub open / close valve 35.
[0026]
As a result, a difference occurs in the pressure acting on the upper and lower surfaces of the main spool 24, and the main spool 24 is lowered. As shown in FIG. The air supply to the air motor 4 is cut off and the air motor 4 is stopped.
[0027]
When the screw driving machine 1 is lifted from the object to be screwed after the air motor 4 is stopped, the contact arm 18 is lowered and separated from the stem 33. Then, the stem 33 and the pilot spool 25 are lowered, the pilot air chamber 23a and the vent port 31 are shut off, and the pilot port 34 and the pilot air chamber 23a communicate with each other to supply pressurized air to the pilot air chamber 23a. The spool 24 floats and returns to the initial position shown in FIG.
[0028]
When the operation of the trigger lever 6 is released, the trigger valve 7 is closed and pressurized air is supplied to the pilot air chamber 43 of the pneumatic cylinder 3, and the head valve 42 of the pneumatic cylinder 3 is lowered to the initial position shown in FIG. Returning, the piston 10 and the driver bit 11 are raised by the pressure of the blowback chamber 44 formed on the lower outer periphery of the pneumatic cylinder 3 and return to the initial position. When the piston 10 rises from the bottom dead center and passes through the outlet port 3b in the pneumatic cylinder 3, the pressure supply from the pneumatic cylinder 3 to the pilot port 41 of the secondary opening / closing valve 35 is cut off, and the secondary switching valve 35 spool 37 is lowered to return to the initial position shown in FIG. 3, and the inlet port 39 and the vent port 40 are shut off.
[0029]
Next, due to an excessive pressing load, the driver bit 11 and the piston 10 are pushed into the screw driving machine body during screwing, and the contact arm 18 pushes up the stem 33 and the pilot spool 25 of the on-off valve 22 to the exhaust position before the screwing is completed. This case is shown in FIG. As shown in the figure, the pilot spool 25 is pushed upward by the stem 33, the pilot air chamber 23a on the lower surface of the main spool 24 and the vent port 31 communicate with each other, and the pilot air chamber 23a and the pilot port 34 are shut off. However, since it is before the completion of screwing, the piston 10 is in a position before reaching the bottom dead center, and the auxiliary opening / closing valve 35 is kept closed.
[0030]
Accordingly, the pilot pressure acting on the lower surface of the main spool 24 is not exhausted, and the air supply to the air motor 4 is continued because the main spool 24 maintains the initial position. When the screwing is completed and the piston 10 reaches the bottom dead center, the auxiliary opening / closing valve 35 is opened, the main spool 24 is lowered to the state shown in FIG. 5, and the air motor 4 is stopped.
[0031]
Contrary to the above, if the load for pressing the screwing machine 1 against the object to be screwed is insufficient and the screwing machine 1 is separated from the surface of the screwing object by the reaction force at the time of screw driving, In the same manner as in the state shown in FIG. 4, the piston 10 reaches the bottom dead center before the screwing is completed and the auxiliary opening / closing valve 35 opens. However, since the contact arm 18 is separated from the stem 33 that operates the opening / closing valve 22, the opening / closing valve 22 Maintains the open state, and the air motor 4 continues to rotate. When the screwing is completed and the contact arm 18 pushes up the stem 33 and the pilot spool 25, the air in the pilot air chamber 23a on the lower surface of the main spool 24 is exhausted through the sub-opening / closing valve 35, as shown in FIG. As shown, the main spool 24 descends to cut off the air supply to the air motor 4 and the air motor 4 stops.
[0032]
Note that the present invention is not limited to the above-described embodiment, and various modifications are possible within the technical scope of the present invention, and the present invention naturally extends to those modified ones.
[0033]
【The invention's effect】
As described above, in the automatic stopping device for a screw driving machine according to the present invention, the contact arm for operating the on-off valve provided in the air supply path to the air motor reaches the top dead center, and the piston and the driver bit are bottom dead. When the vicinity of the point is reached, the on-off valve is closed and the air supply to the air motor is stopped.
[0034]
Therefore, the contact arm is pushed to the top dead center position before the screwing is completed due to an excessive pressing load, or the screwdriver is moved away from the surface of the screwing target object due to insufficient pressing load, and the piston reaches the bottom dead center. Even in this case, the air motor continues to rotate, and when the contact arm reaches the top dead center and the piston reaches the bottom dead center, the on-off valve is closed and the air motor stops.
[0035]
In this way, the air motor reliably continues to rotate until screwing is complete, regardless of the pressing load of the screwdriver, so there is no screw tightening failure and the screwing amount is controlled to a constant level of accuracy. It is an invention that contributes to ease of operation.
[Brief description of the drawings]
FIG. 1 is a sectional view of a screw driving machine.
FIG. 2 is a side view of the screw driving machine.
FIG. 3 is a partial cross-sectional view of a screw driving machine showing an automatic stop device.
4 is a partial cross-sectional view of the screw driving machine showing a state in which the auxiliary on-off valve shown in FIG. 3 is opened.
FIG. 5 is a partial cross-sectional view of the screw driving machine showing a state where the on-off valve and the sub on-off valve shown in FIG. 3 are opened.
FIG. 6 is a partial cross-sectional view of the screw driving machine showing a state in which the contact arm is pushed in by an excessive pressing force.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Screwdriver 2 Housing 3 Pneumatic cylinder 4 Air motor 10 Piston 11 Driver bit 14 Nose part 18 Contact arm 22 On-off valve 23 Valve sleeve part 23a Pilot air chamber 24 Main spool 25 Pilot spool 28 Inlet port 29 Outlet port 31 Vent port 33 Stem 34 Pilot Port 35 Sub Open / Close Valve 36 Valve Sleeve 37 Spool 39 Inlet Port 40 Vent Port 41 Pilot Port

Claims (1)

A driver bit formed with a bit that engages with the screw head at the tip of the spline shaft is rotatably connected to the piston of the pneumatic cylinder, and the driver bit is inserted into a gear formed with a center hole with a spline groove, An air motor for rotating the driver bit, driving the piston of the pneumatic cylinder and driving a screw with the driver bit, and driving the driver bit with the air motor to screw the screw,
An open / close valve is provided in the air supply path to the air motor, a contact arm that is slidable along the nose part of the screw driving machine is provided, and the contact arm is urged in the direction of screw injection by a spring to tip the tip of the contact arm. also projecting from the part, a stem for opening and closing operation of the vent port of the pilot air chamber of the on-off valve is opposed to the other end of the contact arm, the contact arm is the stem to be pushed into the screw gun body with the progress of screwing opening the vent port by pressing an automatic stop device of the configuration the screw driving machine as the on-off valve to stop the air motor by close,
A sub-open / close valve is installed in parallel with the open / close valve, and the spool in the valve sleeve portion of the sub-open / close valve is urged downward by a spring so that the inlet port of the sub-open / close valve and the vent port provided above it The pilot port provided at the lower part of the auxiliary on-off valve is connected to the outlet port provided at the lower end of the pneumatic cylinder, and the piston of the pneumatic cylinder is further connected to the bottom dead center. when reaching the outlet port pressure air in the air pressure cylinder is discharged is provided on the tip vicinity of the air pressure cylinder, and connect the outlet port to the pilot port of the auxiliary switching valve, the piston bottom dead center portion It reached the auxiliary switching valve is open, and, when the contact arm is pressed stem of the on-off valve, pressure air in the pilot air chamber of the on-off valve is evacuated through the sub-off valve, Automatic stop device for a screw driving machine, characterized in that closing is closed air motor is configured to stop.

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