JPS63189B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the mechanism of an electric screwdriver, which allows a bit to be attached to and removed from the rotating shaft of the electric screwdriver to be easily and quickly carried out.

In devices such as electric screwdrivers that use electric power or other power to drive screws into workpieces, the bits are easily damaged because it is difficult to tighten the screws by hand, especially when screws made of steel S as shown in Figure 1 are used. In screw tightening machines that continuously drive bits into steel plates, the bits are often damaged, so it is desired that the bits be easily removed from the rotating shaft on which they are attached, and that the bits be easily attached.

In this invention, a rotating shaft for holding a bit is provided to protrude from the motor housing from such a point, and a sleeve that slides on the shaft in the longitudinal direction of the shaft is always placed at a specific position on the rotating shaft. The bit shaft is inserted into a square hole of a specific depth provided at the front end of the rotating shaft, and a small hole is passed through the bit shaft at a position corresponding to a groove provided at a specific position. A small ball having a size such that a part of the ball protrudes from the small hole into the groove in the rectangular hole is fitted into the small hole, and a small ball is fitted into the sleeve at a position shifted forward from the position of the small hole. It is characterized by having a concave groove large enough to allow a portion of the small ball to fall into the inner surface of the sleeve, so that the bit can be removed without resisting the urging force acting on the sleeve. When the sleeve is pushed toward the rear of the rotating shaft and the groove on the inner surface of the sleeve is aligned with the small hole in the rotating shaft, the small ball in the small hole can partially fall into the sleeve groove. If you align them like that and pull out the bit from the rotating shaft,
Due to the movement of the groove, the small ball that had partially fallen into the groove of the bit moves inside the small hole towards the groove of the sleeve and comes out of the groove of the bit, and thus the bit can be easily pulled out from the square hole. be able to. In the removed state, when another bit is inserted into the square hole and the pushing action on the sleeve is released, the sleeve returns to its original position due to the biasing force acting on it.
At this time, the small ball that had partially fallen into the sleeve groove is pushed out of the small hole toward the bit groove, and the bit is thus securely held within the square hole. The replacement operation can be performed extremely easily and quickly, and an excellent bit holding device that can securely hold the bit in the square hole has been achieved.

In the embodiment shown in FIG. 2 of the accompanying drawings, the electric screwdriver has a rotating shaft 22 whose front end protrudes from a motor housing 100 and rotates, and a bit 2 that is inserted into a square hole 23 formed in the front end of the rotating shaft 22.
0 and a sleeve 21 fitted over the rotating shaft 22.

The bit 20 is rotatably supported by a rotating shaft 22 incorporating the bit in a bearing 80 incorporated in the housing 100, and the rotating shaft 22 is also configured to be able to slide somewhat rearward. Due to the sliding mechanism, the rotating shaft 22 is engaged with a transmission shaft 81 at the rear thereof, and a female clutch 25 formed at the rear end of the rotating shaft 22 collides with the bearing 80 by means of a spring 24 (shown in dotted lines) incorporated between the rotating shaft 22 and the transmission shaft 81 at the rear. Normally, the female clutch 25 is separated from its corresponding male clutch 82. Note that this male clutch 82 is formed at the front end of the transmission shaft 81.

With the above configuration, the bit 20 is applied to the head of the screw to be screwed into the workpiece, and the motor housing 100 is
When the whole is operated by means of its handle 10 (see FIG. 1) to push the screw into the workpiece, the bit 20 slides backwards against the resiliency of the spring 24 on the rotating shaft 22 to which it is attached, and thus rotates. The female clutch 25 of the shaft 22 is coupled with the male clutch 82 and receives rotation from the already rotating transmission shaft 81 by turning on the switch 10' provided on the handle 10.
Screw the screw into the workpiece.

When screwing the screw into the workpiece is completed and the bit 20 is pulled away from the screw head together with the motor housing 100, the thrust applied to the rotating shaft 22 disappears, so the rotating shaft 22 is immediately returned to its original position by the spring 24. The female clutch 25 is released from the male clutch 82 and its rotation is stopped.

A mechanism for easily removing or attaching the bit 20 from the rotating shaft 22 is provided on the rotating shaft 22.
Prepared for 2. That is, a square hole 23 of a specific depth is bored at the front end of the rotating shaft 22, and a bit square shaft 20' is inserted into the square hole 23. The mechanism for locking the inserted bit square shaft 20' in the square hole 23 is to form a groove 26 on the circumferential surface of the bit square shaft 20' at an appropriate position in the square hole 23, and A small hole 28 is provided in the rotating shaft 22 corresponding to the square hole 23 to pass through the outer surface of the rotating shaft 22, and a small ball 27 is fitted into the small hole 28, and a part of the small ball 27 is inserted through the small hole 28. The size is such that it can be pushed into the groove 26.
In this way, most of the small ball 27 exists in the small hole 28, and a part of it protrudes into the concave groove 26 of the bit angle shaft 20'.
0' is securely locked in the square hole 23.

However, the concave groove 26 of the bit angle shaft 20' has an arc shape as shown in the figure, so if only the above-mentioned configuration is used, if the bit angle shaft 20' is pulled out of the square hole 23, the concave groove 26 will protrude into it. The small ball 27 is pushed out into the small hole 28, so that the small ball 27 moves inside the small hole 28 and a part of it protrudes to the outer surface of the rotating shaft 22, and the square shaft 20' is pushed out from the square hole 23. It comes off easily. By preventing such movement of the small ball 27 within the small hole 28, the bit square shaft 20' can be reliably locked within the square hole 23. However, the bit square shaft 20' must be easily removed from the square hole 23. In this way, the sleeve 21 is fitted over the rotating shaft 22, and the sleeve 21 has a groove 29 on its inner surface into which a part of the small ball 27 can be thrust. The position of the small hole 28 is inconsistent with that of the small hole 28.

In order to maintain this discrepancy at all times, the inner end 21' of the sleeve 21 is located within the motor housing 100, and a resilient spring 85 provided within the housing 100 is applied to the inner end 21'. Thus, in order to pull out the bit square shaft 20' from the square hole 23,
If the sleeve 21 is pushed into the housing 100 against the elasticity of the spring 85 acting on it and the sleeve groove 29 is aligned with the small hole 28, the small ball 27 that was partially depressed in the bit groove 26 will be removed. When the bit angle shaft 20' is pulled out, the bit angle shaft 20' easily moves within the small hole 28 and partially falls into the sleeve recessed groove 29, so that the bit angle shaft 20' easily comes out of the square hole 23.

As described above, the bit holding device of the present invention is an excellent device that allows easy and quick operations for attaching and detaching the bit square shaft to the square hole.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a screw tightening machine using the bit holding device of the present invention, and FIG. 2 is a partially cutaway side view showing an embodiment of the bit holding device of the present invention. 20 is a bit, 20' is a bit square shaft, 21 is a sleeve, 22 is a rotating shaft, 23 is a square hole, 25 is a female clutch, 26 is a bit concave groove, 27 is a small ball, 28 is a small hole, 29 is a sleeve concave Groove, 81 is transmission shaft, 82
85 is a male clutch, 85 is a spring, and 100 is a motor housing.

Claims (1)

[Claims] 1. A square hole of a specific depth is drilled from the front end of the shaft on the center line of the rotating shaft that protrudes from the motor housing and rotates when driven by the electric motor, and the square shaft is large enough to be inserted into the square hole. In an electric screwdriver that is used for driving a screw by inserting a held bit into the square hole, a sleeve that slides on the rotating shaft in the front-rear direction of the shaft is always kept at a specific position on the shaft. A small hole is provided in the rotating shaft at a position corresponding to a groove provided at a specific position of the bit shaft inserted into the square hole, and a small hole is provided in the small hole. A small ball having a size that causes a portion to protrude from the small hole into the groove in the square hole is fitted into the sleeve, and one of the small balls is inserted into the inner surface of the sleeve at a position shifted forward from the position of the small hole. A bit holding device with a groove large enough for the part to fall into.