JP3716798B2 - Screwing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw fastening device (mainly an electric screwdriver) used when screwing a gypsum board or the like used for a ceiling or a wall.
[0002]
[Prior art]
A screw tightening device such as an electric screwdriver is mainly used for a material to be tightened such as a gypsum board. Since this screw tightening device requires a fixed depth for screw tightening, a stopper that can be moved in the axial direction is provided on a part of the main body. When the main body moves to a position where the stopper comes into contact with the member to be fastened, there is provided a screw tightening depth adjusting mechanism that performs a clutch disengagement operation. On the other hand, in the case of the screw loosening operation at the time of reverse rotation, a mechanism for transmitting power by a one-way clutch is provided.
[0003]
A screw tightening device disclosed in Japanese Patent Laid-Open No. 8-267367, which is an example of a conventional screw tightening device, will be described below with reference to FIG.
[0004]
In FIG. 1, a stopper sleeve 3 is screwed and attached to the tip of the housing 2 of the screw tightening device. By rotating the stopper sleeve 3 with respect to the housing 2, the relative distance between the stopper sleeve 3 and the housing 2 can be adjusted, whereby the screw feed distance (screw tightening depth) can be adjusted.
[0005]
In the housing 2, a pinion 19 attached to an output shaft of a motor (not shown) is engaged with a gear 5 provided on the outer periphery of the drive shaft member 4, and the drive shaft member 4 and the gear 5 are integrated in the rotation direction. Therefore, the rotation of the motor is transmitted to the drive shaft member 4 through the gear 5.
[0006]
The clutch spring 6 which is a compression spring is left-handed as shown in FIG. 2, and has an upper end and a lower end extending in the axial direction.
[0007]
An output shaft member 7 that has an engagement ball 18 and accommodates the bit 10 so as to be integrally rotatable by the engagement ball 18 is supported by the metal portion 8 so as to be rotatable and axially movable, and moves toward the bit 10 side. The position is regulated. The output shaft member 7 has a portion located in the one-way clutch 16 held in the drive shaft side sleeve 4a of the drive shaft member 4, and the output shaft member 7 can move in the one-way clutch 16 in the axial direction. The one-way clutch 16 can be rotated only in one direction (screw tightening direction) with respect to the one-way clutch 16.
[0008]
A stopper member 3 is provided at the end of the stopper sleeve 3 on the side of the drive shaft 4 so as to be non-rotatable and movable in the axial direction. An uneven claw portion provided so as to mesh with each other is engaged with the contact portion of the stopper sleeve 3 and the lock member 12. Therefore, in a state where the claw portion of the stopper sleeve 3 and the claw portion of the lock member 12 are engaged with each other, the stopper sleeve 3 cannot rotate with respect to the housing 2 and the axial position is fixed. The screw tightening depth is adjusted by the operator sliding the lock member 12 toward the drive shaft member 4 against the compression spring 11 and engaging the stopper sleeve 3 with the claw portion of the lock member 12. This can be done by rotating the stopper sleeve 3 relative to the housing 2 in the released state.
[0009]
An umbrella-shaped member 13 provided in the drive shaft member 4 so as to be movable in the axial direction is in contact with the end of the output shaft member 7 on the side opposite to the bit 10, and a tapered portion 13 a on the outer periphery of the umbrella-shaped member 13 The ball 9 provided so as to be movable in the radial direction is in contact with a through hole 4b provided in the drive shaft side sleeve 4a, and the umbrella-like member 13 is always pressed against the output shaft member 7 by a spring 15. ing.
[0010]
In the state shown in FIG. 1, the bit 10 and the output shaft member 7 are moved downward in the drawing by the pressing force of the spring 15 via the umbrella-shaped member 13, and the tip end portion of the bit 10 is protruded from the tip end of the stopper sleeve 3. is there.
[0011]
By starting the screw tightening operation from this state, the bit 10 and the output shaft member 7 move axially upward in the figure while resisting the pressing force of the spring 15 via the umbrella-shaped member 13.
[0012]
When the bit 10 and the output shaft member 7 move in the axial direction in this way, the tapered portion 13a of the umbrella-like member 13 that is inclined so that the outer diameter dimension gradually decreases as the distance from the output shaft member 7 is increased. The contacting ball 9 protrudes to the outer periphery of the drive shaft side sleeve 4a.
[0013]
The output shaft member 7 is provided with an output shaft side sleeve 7a having an outer diameter substantially the same as that of the drive shaft side sleeve 4a. The output shaft side sleeve 7a includes the output shaft side sleeve 7a and the drive shaft side. The end of the clutch spring 6 positioned on the outer periphery of the side sleeve 4a is fixed to the fixed portion 14a and the end surface of the clutch spring 6 and protrudes to the outer periphery of the output shaft side sleeve 7a that regulates the axial position of the clutch spring 6. A protruding portion 14b is provided. Further, the end portion of the clutch spring 6 fixed to the fixing portion 14a is bent as shown in FIGS. 2 and 3, and is attached so as not to move in the axial direction.
[0014]
The end 6a of the clutch spring 6 on the drive shaft member 4 side is a free end, and when the bit 10 and the output shaft member 7 move in the axial direction, they move in the axial direction in conjunction with each other.
[0015]
During the screw tightening operation, when the bit 10 and the output shaft member 7 move in the axial direction against the spring 15, the end 6 a on the drive shaft member 4 side of the clutch spring 6 moves in the axial direction in conjunction with the output shaft member 7. , Located on the outer periphery of the ball 9. As the bit 10 and the output shaft member 7 move, the umbrella-shaped member 13 moves in the axial direction, and the ball 9 protrudes on the outer periphery of the drive shaft-side sleeve 4a by the action of the tapered portion 13a of the umbrella-shaped member 13. Therefore, the end 6 a of the clutch spring 6 on the drive shaft member 4 side and the ball 9 abut on each other in the rotational direction of the drive shaft member 4, and the rotational force of the motor is transmitted via the gear 5, the drive shaft member 4, and the ball 9. It is transmitted to the clutch spring 6.
[0016]
When the motor is rotating forward, the clutch spring 6 is deformed to reduce the outer diameter, wound around the outer periphery of the drive shaft side sleeve 7a and the outer periphery of the output shaft side sleeve 4a, and works to rotate both members together. As a result, the rotational force of the drive shaft member 4 is transmitted to the output shaft member 7 via the clutch spring 6, and the bit 10 rotates to perform the screw tightening operation.
[0017]
As the screw tightening operation proceeds, the end surface of the stopper sleeve 13 comes into contact with the member to be tightened. As the screw is tightened, the bit 10 and the output shaft member 7 are pushed by the pressing force of the spring 15 to the tip of the bit 10. Move axially to the side. When the bit 10 and the output shaft member 7 move by a predetermined amount toward the tip end side of the bit 10, the ball 9 that contacts the tapered portion 13a of the umbrella-shaped member 13 and protrudes on the outer periphery of the drive shaft side sleeve 4a does not protrude. As a result, the winding of the clutch spring 6 on the outer periphery of the drive shaft side sleeve 4a and the outer periphery of the output shaft side sleeve 7a is released, the rotation transmission of the output shaft member 7 and the bit 10 is cut off, and the screw tightening operation is completed.
[0018]
[Problems to be solved by the invention]
The conventional screw tightening device as described above has a structure in which the end of the screw tightening operation is performed by sinking the ball 9 by the axial movement of the output shaft member 7 and the umbrella-shaped member 13. Since 6a is locked to the fixed portion 14a of the output shaft member 7, the clutch spring 6 moves in the axial direction on the output shaft side sleeve 7a as the output shaft member 7 moves. When the ball 9 sinks and the rotation operation is interrupted, the clutch spring 6 returns to the initial state (a state in which the coils are in close contact), but there is a gap in the coil interval partially depending on the state of the outer peripheral surface of the output shaft member 7 and the like. As shown in FIG. 4, the coil spring 6 may be deformed to occur, or the end of the coil spring 6 may not be in contact with the protruding portion 14b (the state does not return to the initial state). Although the bit 10 and the drive shaft member 4 do not move axially against the spring 15, the end of the clutch spring 6 on the drive shaft member 4 side protrudes on the outer periphery of the ball 9, or as shown in FIG. Thus, the end 6a of the clutch spring 6 may be inclined with respect to the shaft as compared with the normal state.
[0019]
When screw tightening is performed with the end portion 6a of the clutch spring 6 as shown in FIG. 4, the end portion 6a of the clutch spring 6 enters into the drive side sleeve 4a more than usual. When the rotation transmission to the member 7 is interrupted, there is a problem that the timing at which the contact between the end 6a of the clutch spring 6 and the ball 9 is released is delayed, and the screw tightening depth becomes deeper than the setting.
[0020]
Further, if the screws are tightened with the clutch spring 6 tilted, the end portion 6a of the clutch spring 6 is caught in the groove of the drive shaft side sleeve 4a, and the rotation transmission to the output shaft member 7 cannot be cut off. In addition, there is a problem that the phenomenon that the output shaft member 7 and the bit 10 continue to rotate (corotation) occurs.
[0021]
The present invention eliminates the above-mentioned drawbacks and prevents the clutch spring from moving in the axial direction on the shaft member on the fixed side. Is to provide.
[0022]
[Means for Solving the Problems]
The purpose is to separate the drive shaft member that transmits power from the drive device, the output shaft member that holds the bit and is movably supported in the axial direction, and the output shaft member and the drive shaft member from each other. A pressing means that acts on the same axis as the drive shaft member and the output shaft member, and is arranged in a coil shape across each cylindrical surface, and a part is fixed to either the output shaft member or the drive shaft member, And a screw tightening device having a clutch spring that can be locked to the other member in accordance with the movement of the output shaft member, and a one-way clutch that is mounted between the drive shaft member and the output shaft member. This is achieved by providing a convex portion for restricting movement of the clutch spring in the axial direction on the outer periphery of the fixed shaft member that fixes the shaft.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the screw tightening device of the present invention will be described below with reference to FIGS. In addition, in this embodiment, since it is the structure similar to the conventional screw fastening apparatus about parts other than the output shaft member 7, description is abbreviate | omitted.
[0024]
6 is a perspective view showing an embodiment of an output shaft member constituting the screw tightening device of the present invention, FIG. 7 is a sectional view taken along line AA of FIG. 6, and FIG. 8 is an output shaft member constituting the screw tightening device of the present invention. It is a perspective view which shows other embodiment.
[0025]
As shown in FIGS. 6 and 7, on the outer periphery of the output shaft side sleeve 7a of the output shaft member 7 that fixes one end of the clutch spring 6, there is a fixed wall 14a that engages with one end of the clutch spring 6 and the clutch spring 6 Are provided with a plurality of protrusions 17 projecting on the output shaft side sleeve 7a and extending in a direction perpendicular to the axial direction.
[0026]
As shown in FIG. 7, the interval between the projections 17 is formed so that the projections 17 protrude between the coils of the clutch spring 6, whereby the clutch springs are placed on the output shaft side sleeve 17 a of the output shaft member 17. When 6 is disposed, the convex portion 17 functions to regulate the position of the clutch spring 6 in the axial direction.
[0027]
With such a configuration, when the bit 10 and the output shaft member 7 are moved away from the drive shaft member 4 by the pressing force of the spring 15 just before the end of screw tightening, the clutch spring 6 is moved to the output shaft side sleeve 17a. Therefore, the clutch spring 6 is deformed so that the coil interval is widened on the output shaft side sleeve 17a, and the end surface of the clutch spring 6 is in contact with the protruding portion 14b. It is possible to prevent tilting with respect to the axis without doing so. As a result, it is possible to suppress over-tightening of the screw and the occurrence of the co-rotation phenomenon, and it is possible to stabilize the contact state between the end 6a of the clutch spring 6 and the ball 9 at the next screw tightening. Even when the screw tightening operation is repeatedly performed on the material to be tightened, the rotation transmission blocking position becomes constant, and the accuracy of the screw tightening depth can be improved.
[0028]
In the above embodiment, a plurality of convex portions 17 projecting on the output shaft side sleeve 7a are provided, and stress is prevented from concentrating on a part of the clutch spring 6 that contacts the convex portion 17. However, even when the single protrusion 17 is provided, the clutch spring 6 can be prevented from moving in the axial direction on the output shaft side sleeve 17a.
[0029]
In addition, as shown in FIG. 8, the above-described convex portion 17 protrudes in a spiral shape having the same shape as the clutch spring 6, so that the contact area between the clutch spring 6 and the convex portion 17 can be increased. In this case, it is possible to further suppress the stress from being concentrated on a part of the clutch spring 6 that contacts the convex portion 17.
[0030]
In the present embodiment, the shaft member on the fixed side that fixes the end of the clutch spring 6 that works to rotate the drive shaft side member 4 and the output shaft member 7 integrally at the time of forward rotation is referred to as the output shaft member 7. The shaft member that holds the ball 9 that can come into contact with the end portion 6a of the clutch spring 6 in conjunction with the axial movement of the output shaft member 7 is the drive shaft side member 4. The shaft member on the fixed side that fixes the end of the spring 6 may be the drive shaft member 4, and the member that holds the ball 9 may be the output shaft member 7. In this case, the convex portion 17 is provided on the drive shaft side sleeve 4a. The clutch spring 6 is configured to suppress the axial movement of the clutch spring 6 on the drive shaft side sleeve 4 a of the drive shaft member 4.
[0031]
Next, another embodiment of the screw fastening device of the present invention will be described with reference to FIG.
[0032]
In this embodiment, in place of the ball 9 and the umbrella-shaped member 13 used as means for locking the end 6a of the clutch spring 6 to the drive shaft member 4 when the output shaft member 7 moves in the axial direction in the above embodiment. The end portion 6a of the clutch spring 6 can be accommodated in the drive shaft member 4, and a tapered portion 4c is provided that can sandwich the end portion 6a when the clutch spring 6 moves to the drive shaft member 4 side. However, the present invention can be adopted even with a screw tightening device having such a configuration.
[0033]
【The invention's effect】
As described above, according to the present invention, the protrusion that restricts the axial movement of the clutch spring is fixed to the fixed-side shaft member that fixes the end portion of the clutch spring that integrally rotates the drive shaft member and the output shaft member. By providing the portion, it is possible to provide a screw tightening device with high accuracy of the screwing depth in the screw tightening operation.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of a main part showing an example of a conventional screw fastening device.
FIG. 2 is a perspective view showing an example of a clutch spring used in a screw tightening device.
FIG. 3 is a perspective view showing a state in which a clutch spring is fixed to a conventional output shaft member.
FIG. 4 is an enlarged cross-sectional view of a main part showing one operation state of a conventional screw fastening device.
FIG. 5 is an enlarged cross-sectional view of a main part showing one operation state of a conventional screw tightening device.
FIG. 6 is a perspective view showing an embodiment of an output shaft member constituting the screw fastening device of the present invention.
7 is a cross-sectional view taken along line AA in FIG.
FIG. 8 is a perspective view showing another embodiment of the output shaft member constituting the screw fastening device of the present invention.
FIG. 9 is an enlarged cross-sectional view of a main part showing another embodiment of the screw fastening device of the present invention.
[Explanation of symbols]
1 is a screw tightening device, 2 is a housing, 3 is a stopper sleeve, 4 is a drive shaft member, 4a is a drive shaft side sleeve, 4b is a through hole, 5 is a gear, 6 is a clutch spring, 6a is an end of the clutch spring, 7 is an output shaft member, 7a is an output shaft side sleeve, 8 is a metal member, 9 is a ball, 10 is a bit, 11 is a compression spring, 12 is a lock member, 13 is an umbrella-like member, 14a is a fixed portion, and 14b is protruding. , 15 is a spring, 16 is a one-way clutch, 17 is a projection, 18 is an engagement ball, and 19 is a pinion.

Claims (4)

A drive shaft member that transmits power from the drive device, an output shaft member that holds the bit and is supported so as to be movable in the axial direction, and acts to separate the output shaft member and the drive shaft member from each other. Coaxially arranged between the pressing means, the drive shaft member, and the output shaft member so as to straddle each cylindrical surface, and a part is fixed to either the output shaft member or the drive shaft member A screw fastening device having a clutch spring that can be locked to the other member according to the movement of the output shaft member, and a one-way clutch attached between the drive shaft member and the output shaft member, A screw tightening device, wherein a convex portion for restricting movement of the clutch spring in the axial direction is provided on an outer periphery of a fixed shaft member for fixing a part of the clutch spring. The fixed-side shaft member is an output shaft member, and the drive shaft member holds a ball that moves in the radial direction in accordance with the axial movement of the output shaft member and can come into contact with the end of the clutch spring. The screw fastening device according to claim 1, wherein The screw tightening device according to claim 1 or 2, wherein a plurality of the convex portions are provided, and an interval between the convex portions is formed at the same interval as a coil interval of the clutch spring. The screw tightening device according to any one of claims 1 to 3, wherein the convex portion is formed in a spiral shape similar to the clutch spring.

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