JPS6110932Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of an electric screwdriver (hereinafter abbreviated as an electric screwdriver), and particularly to a switch portion that controls starting and stopping thereof.

[Conventional technology]

For example, Japanese Utility Model Application Publication No. 56-48472 discloses an electric screwdriver as shown in FIG. Referring to FIG. 1, a cylindrical frame 11 is composed of an adjusting screw 12, a tightening tube 13, a frame handle 14, and a cover 15. A bit holder 16 is rotatably supported in the adjustment screw 12 of the frame 11 by a ball bearing 17. The bit holder 16 is also movably supported in the axial direction and is biased in the direction of arrow 19 by a spring 18. The movement of the bit holder 16 in the direction of the arrow 19 is stopped when a retaining ring 21 provided on the circumferential surface of the bit holder 16 engages with the ball bearing 17. A bit 22 is attached to one end of such a bit holder 16.

An electric motor 23 for applying rotational force to the bit holder 16 is provided inside the frame handle 14. The electric motor 23 rotates a cam 25 supported by a ball bearing 24 via a reduction gear part 26.

A ball holder 27 is provided between the bit holder 16 and the cam 25. Ball holder 27
One end of the bit holder 16 is fitted to the other end of the bit holder 16 so as to be movable only in the axial direction. Ball holder 27
The other end is a cylindrical portion 27a, into which a corner portion 25a at one end of the cam 25 is fitted, as shown in FIG. Further, a ball 28 is fitted into a through hole formed in the cylindrical portion 27a so as to be movable in the radial direction.

The bit holder 16 further has a cylindrical member 2 on its outer periphery.
9 is fitted movably in the axial direction. Cylindrical member 29
is urged in the direction of arrow 32 by spring 31. A tapered surface 29a facing the ball 28 is provided on the inner surface of one end of the cylindrical member 29. A tapered surface 29b is also provided on the inner surface of the cylindrical member 29 near the other end. Note that 33 is a thrust bearing for allowing rotation of the cylindrical member 29;
4 is a spring receiver.

Further, on the central axis of the cylindrical frame 11, an elongated rod member 25 is supported movably in the longitudinal direction. The rod member 35 is biased by a spring 36 in the same direction as the bit holder 16, that is, in the direction of the arrow 19. The rod member 35 is moved in the direction of the arrow 19 by a pin 3 attached to the bit holder 16.
It is stopped when the tip hits point 7. A tapered surface 35a is formed near the tip of such a rod member 35. Further, a through hole is formed in the bit holder 16 at a portion facing the tapered surface 35a, and a ball 38 is held in this through hole so as to be movable in the radial direction.

Further, a top 39 is fixed near the other end of the rod member 35. This frame 39 is the start switch 41
and for driving the stop switch 42. Note that 43 indicates a power cord.

Next, the operation will be explained. First, place the tip of the bit 22 against the head of the screw and push the frame 11 toward the bit. At this time, the same state occurs as if the bit holder 16 had been pushed in the direction of the arrow 32 against the spring 18. When the bit holder 16 moves in the direction of the arrow 32, the rod member 35 is also sent in the same direction, so the top 39 pushes the push button 41a of the starting switch 41 to drive the starting switch 41, and the electric motor 23 starts rotating. Further, at this time, the ball 38 is sent by the bit holder 16 to a position facing the tapered surface 29b of the cylindrical member 29. The rotational force of the electric motor 23 is generated by the cam 25
It is further transmitted to the bit holder 16 via the ball 28 and ball holder 27. Thus, by rotating the bit 22, the screw-threading operation is started.

As the screw continues to be screwed in and reaches a predetermined tightening torque, the bit 22 stops rotating together with the screw. When the bit 22 stops, the bit holder 16 and ball holder 27 are also stopped from rotating. On the other hand, since the cam 25 continues to rotate, the corners of the corner portions 25a push the balls 28 radially outward. ball 28
When pushed out, pushes one tapered surface 29a of the cylindrical member 29, thereby moving the cylindrical member 29 in the direction of the arrow 19. In this way, power transmission between the cam 25 and the ball holder 27 is disconnected.

At this time, the other tapered surface 2 of the cylindrical member 29
9b pushes the ball 38 radially inward. The pushed ball 38 engages with the tapered surface 35a of the bar member 35, thereby moving the bar member 35 further in the direction of the arrow 32. That is, the tapered surface 29b, the ball 38, and the tapered surface 35a constitute an overload detection device.

When the rod member 35 further moves in the direction of the arrow 32 in this way, the top 39 presses the push button 4 of the stop switch 42.
By pressing 2a, the stop switch 42 is activated. When the stop switch 42 is activated, the electric motor 23
will stop immediately. Note that even if the top 39 leaves the stop switch 42 after that, the electric motor 23 is kept in an electrically stopped state.

According to the electric screwdriver shown in Fig. 1, when the bit holder is pushed in, the electric motor is driven by the start switch and rotates the bit holder, so tendonitis, which has traditionally been a concern as an occupational disease, can be prevented. Additionally, if a braking force exceeding a certain level is applied to the bit holder, the clutch mechanism interposed between the rotating shaft of the electric motor and the bit holder will disengage, and at the same time, the electric motor will be stopped by the stop switch, so the tightening torque will be reduced. In addition to improving the accuracy of screw tightening, there is no reaction (shock) when tightening is completed due to inertia, which eliminates operator fatigue and discomfort.In addition, an electrical means to rapidly reduce inertia immediately after screw tightening is completed. Since the configuration is such that the overall structure is simple, there are advantages.

[Problem that the invention attempts to solve]

However, the electric screwdriver shown in FIG. 1 has the following problem with the switch portion 44 that controls starting and stopping of the electric motor 23. That is, the push buttons 41a and 41 of the start switch 41 and the stop switch 42 are pressed by the slope of the side surface of the top 39.
Because of the structure in which the push buttons 41a and 41b are pressed, even if the rod member 35 is moved farther, the push buttons 41a and 41b cannot be moved farther, and therefore the start switch 41 and the stop switch 42 cannot be operated reliably. It is difficult to However, if a large piece 39 is used, the overall outer diameter becomes large, impairing operability.

Therefore, an object of the present invention is to provide an electric screwdriver that can be started and stopped automatically and reliably.

[Means for solving problems]

According to the present invention, a frame, a bit holder rotatably and axially movably supported by the frame and biased toward the bit mounting end side, and an electric motor for applying rotational force to the bit holder. a rod member that is movably supported in the longitudinal direction on the axis of the bit holder, is biased in the same direction as the bit holder, and is prevented from moving in the biased direction by having one end locked to the bit holder; , is set by moving the bit holder in the opposite direction to the biasing direction, and when an overload of the bit holder is detected,
an overload detection device that cuts off the transmission of rotational force between the bit holder and the electric motor and further moves the bar member in a direction opposite to the biasing direction; fixed to,
An electric driver including a first switch for starting the electric motor and a second switch for stopping the electric motor, which is disposed on a side of the rod member and fixed to the frame. The first switch has a switch operating portion on a surface facing opposite to the biasing direction of the rod member, and the second switch has a switch operating portion on a surface facing the same direction as the biasing direction of the rod member. , the rod member is provided with first and second arms projecting laterally, the first arm faces the switch operating portion of the first switch in the movable direction of the rod member, and the first arm The second arm faces the switch operation part of the second switch in the movable direction of the bar member, and the second arm includes an arm body attached to a midway portion in the longitudinal direction of the bar member, and an arm body that is attached to the middle part in the longitudinal direction of the bar member. There is obtained an electric screwdriver characterized in that the electric screwdriver is held in the arm body and has an adjusting pin whose protrusion length can be varied and which protrudes from the surface of the arm body facing the second switch.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows an embodiment of the electric screwdriver according to the present invention, and FIG. 4 shows the structure of only the switch portion 44 thereof. Here, the start switch 41 and stop switch 42 face each other with the bar member 35 in between, similar to the electric screwdriver shown in FIG. 1. However, in this embodiment, the activation switch 41 is positioned so as to have a switch operating section consisting of a push button 41a and an operating lever 41b opposite to the push button 41a on the surface of the rod member 35 facing opposite to the biasing direction 19. On the other hand, the stop switch 42 has a push button 42 on the same side as the urging direction 19 of the rod member 35.
It is positioned so as to have a switch operation section consisting of a switch 42a and an operation lever 42b opposite thereto. And start switch 41 and stop switch 42
are connected to each other by a connecting member 45, and are fixed to the cover 15 of the frame 11 as one switch assembly 46. In addition, the operation lever 41
b, 42b are rotatable around one end.

The rod member 35 passes through the connecting member 45. The tip of this rod member 35 is bent at a right angle to form a first arm 47 facing the operating lever 41b of the starting switch 41. In addition, a stop switch 4 is provided in the middle of the rod member 35 in the longitudinal direction, protruding in the right angle direction.
The second arm 4 facing the second operating lever 42b
8 will be provided. The second arm 48 has an arm body 4 attached and fixed to the rod member 35 with a screw 49.
8a, and an adjustment pin 48b made of a threaded part screwed into a threaded hole at the tip of the arm body. The adjustment pin 48b is the stop switch 4
It protrudes to a position opposite to the second operating lever 42b, and is rotated by operating an operating knob 48c integrated therewith, so that the protruding length can be arbitrarily adjusted.

In the electric screwdriver of this embodiment, when the switch part 44 is not in use, as shown in FIG.
1b firmly and press the second arm 4
The adjustment pin 48b of No. 8 is set so as to be separated from the operating lever 42b of the stop switch 42.

Now, when the rod member 35 is moved in the direction of the arrow 32 by pressing the bit 22 against the screw,
As shown in FIG. 5, the first arm 47 separates from the operating lever 41b of the starting switch 41, and accordingly, the electric motor 23 is energized and starts operating. At the same time, the adjustment pin 48b of the second arm 48 is connected to the operating lever 42 of the stop switch 42.
b approaches or contacts, and becomes ready to stop.

Next, when the rod member 35 is further moved in the direction of the arrow 32 due to completion of tightening of the screw and an overload condition is established, the adjustment pin 48b of the second arm 48 is moved as shown in FIG. Stop switch 4
2 operating lever 42b is pressed firmly, and in accordance with this, the electric motor 23 is de-energized and the operation is immediately stopped.

[Effect of idea]

As can be seen from the above description, the electric screwdriver according to the present invention includes a rod member having first and second arms protruding laterally, and the first and second arms are used to move the rod member. By moving the rod member closer to and away from the first and second switches themselves, the switch operation parts of the first and second switches are driven, so the moving distance of the rod member is designed to be large. As a result, the switch operating section can be driven reliably, and starting and stopping operations can be automatically and reliably achieved. Further, the second arm includes an arm body added to a midway portion in the longitudinal direction of the rod member, and a protruding length that is held by the arm body and protrudes from a surface of the arm body facing the second switch. Since it has a variable adjustment pin, it also has the effect that the operating timing of the second switch can be easily adjusted.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of an example of a conventional electric screwdriver, Fig. 2 is a cross-sectional view of only the internal mechanism along the - line in Fig. 1, and Fig. 3 is an example of an electric screwdriver according to the present invention. FIG. 4 is a perspective view of only the switch part in the same embodiment; FIG. 5 is a cross-sectional view of only the main parts showing the screw tightening state in the same embodiment; The figure is also a sectional view of only the main parts showing a state in which the screws have been tightened. 11...Frame, 16...Bit holder, 2
2... Bit, 23... Electric motor, 25... Cam,
26...Reduction mechanism, 27...Ball holder, 28
... Ball, 29 ... Cylindrical member, 35 ... Rod member, 38 ... Ball, 39 ... Top, 41 ... Start switch, 42 ... Stop switch, 44 ... Switch part, 47 ... First Arm, 48...Second arm.

Claims (1)

[Claims for Utility Model Registration] 1. A frame, a bit holder rotatably and axially movably supported by the frame and biased toward the bit mounting end, and a bit holder for applying rotational force to the bit holder. An electric motor, supported movably in the longitudinal direction on the axis of the bit holder, biased in the same direction as the bit holder, and prevented from moving in the biased direction by being locked at one end to the bit holder. It is set by moving a rod member and the bit holder in the opposite direction to the biasing direction, and when an overload of the bit holder is detected, the transmission of rotational force between the bit holder and the electric motor is cut off and the rod member an overload detection device that moves the further in a direction opposite to the biasing direction;
a first switch for starting the electric motor, which is arranged on the side of the bar member and fixed to the frame; and a first switch, which is arranged on the side of the bar member and fixed to the frame, for starting the electric motor. and a second switch for stopping the rod member, the first switch has a switch operating portion on a surface opposite to the biasing direction of the rod member, and the second switch The bar member has a switch operating portion on a surface facing in the same direction as the biasing direction of the member, and the rod member includes first and second arms projecting laterally, and the first arm is configured to operate the first switch. facing the switch operation part of the rod member in the movable direction,
The second arm faces a switch operating portion of the second switch in the direction of movement of the rod member,
The second arm includes an arm body added to the midway of the longitudinal direction of the rod member, and a variable adjustable protrusion length held by the arm body and protruding from the surface of the arm body facing the second switch. An electric screwdriver characterized by having a pin. 2. Utility Model Registration Claim 1. The electric screwdriver according to claim 1, characterized in that the adjustment pin is a threaded part screwed into a threaded hole in the arm body.