JP2828657B2 - Hammer drill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a hammer drill that applies not only rotation to a bit but also impact impact in the axial direction.

[Prior art]

As a tool for drilling in concrete, there is a tool called a hammer drill. This is disclosed in JP-A-57-1027.
As shown in Japanese Patent Publication No. 79, a motor, a spindle that is driven to rotate by the motor and holds a bit, and a striking unit that is connected to the motor via a motion conversion member and applies a striking impact to the bit are provided. The striking portion further applies a striking impact to the bit that is rotationally driven. In such a drilling operation, a drill bit 8a shown in FIG. The drill bit 8a is provided with an engagement hole 80 on the outer peripheral surface of a base portion thereof. The key of the chuck provided on the spindle engages with the engagement hole 80 so that the drill bit 8a rotates together with the spindle. To be. Here, a hammer drill may be equipped with a hanging bit 8b shown in FIG. The hanging bit 8b is used to simply break an object to be drilled or to correct irregularities on a surface to be drilled into a certain shape.However, the hanging bit 8b is generally rotated. It is used only for blows. However, with the conventional hammer drill, it was not possible to apply only a hit to the bit, so an engaging groove 81 is provided at the base of the hanging bit 8b over the entire circumference, and the chuck groove is provided in the engaging groove 81. The key is engaged so that the engagement between the key and the engagement groove 81 does not restrict the rotation, so that only the impact is applied to the bit 8b.

[Problems to be solved by the invention]

However, in this case, the following problem occurs. That is, as the fishing bit is pressed against the surface to be drilled, the friction between the rotating chuck and the bit increases, and the bit tends to rotate. For this reason, when performing the hanging work, the lever provided on the bit must be strongly held to prevent the bit from rotating, and the workability is poor. In addition, if the hanging operation is performed for a long time, the chuck and the bit may be seized due to frictional heat, and the safety is lacking. The present invention has been made in view of such a point, and an object of the present invention is to provide a hammer drill capable of performing a hanging operation with good workability.

[Means for Solving the Problems]

Thus, the present invention provides a motor, a spindle rotatably driven by the motor and holding a bit,
A hammer drill having a hitting portion connected to the motor via a motion converting member to apply a hitting impact to the bit, wherein a power transmission between the motor and the motion converting member is provided between the motor and the motion converting member. And first clutch means for controlling power transmission between the motor and the spindle, and second clutch means for controlling power transmission between the motor and the spindle. A single clutch plate to which the clutch plate is transmitted is used as a common clutch element, connection and disconnection are performed by axial movement of the clutch plate, and the clutch plate holding the connection of both clutch means at an intermediate position. The first clutch means is disengaged by one-way movement, and the second clutch means is disengaged by the other movement of the clutch plate. It has a feature to. [Operation] In the present invention, by disconnecting the first clutch means and connecting the second clutch, only rotation can be given to the bit, and the first clutch is connected and the second clutch is connected. By doing so, rotation and impact can be applied to the bit, and further, only the impact can be applied to the bit by connecting the first clutch and disconnecting the second clutch. EXAMPLES Hereinafter, the present invention will be described in detail based on illustrated examples. First, the overall structure will be described. As shown in FIG. 4, the main body housing 1 has a chuck portion 13 at the front end of which a drill bit 8 is mounted, and a handle portion 16 extends from the lower rear end. The battery pack 9 is detachably attached to the lower end of the handle 16. In the figure, 14 is a switch handle, 15 is a rotation direction switching handle, 12 is a motor mount, and 11 is a housing which also serves as a gear case. As shown in FIG. 1, the motor 2 is housed in the rear portion of the main body housing 1 in a state where the axial direction is the front-rear direction, and a pinion 21 is fixed to an output shaft 20 thereof. The pinion 21 is engaged with a reduction gear 24 press-fitted and fixed to one end of an intermediate shaft 23 rotatably supported at both ends by bearings 22 and 22 by a housing 11 and a motor mount 12. An intermediate shaft whose axis is parallel to the motor 2
23 has a pinion 25 at its other end, which is freely rotatably mounted, and a motion converting member 5 at its one end, which is freely rotatably mounted. The clutch plate 28 is mounted. On the other hand, a spindle 31 rotatably supported by a bearing 30 is provided in the front end of the main body housing 1. The spindle 31 has a gear 32 engaged with the pinion 25 fixed to the outer peripheral surface of the rear end thereof. Thus, the chuck 13 is configured to hold the bit 8 so as to be freely slidable in the axial direction within a predetermined range. In the figure, reference numeral 34 denotes a locking member fixed inside the spindle 31 to restrict the sliding range of the striker 33 in the axial direction. On the other hand, behind the striker 33, the piston 4 and the striking body
41 are installed. The piston 4 is slidably held in a direction parallel to the axial direction of the intermediate shaft 23 and the spindle 31 by a motor mount 12 to which the motor 2 is mounted, and is connected to the motion conversion member 5. The piston 4 having a closed-bottom cylindrical shape with a closed rear end houses a striking body 41 slidably therein. The motion converting member 5 converts a rotary motion into a reciprocating motion, and as shown in FIG. 5, a spherical body 50 through which the intermediate shaft 23 is inserted, and a plurality of balls 51 on the outer peripheral surface of the spherical body 50. A ring 52 slidably attached via a ring 52, a shaft 53 protruding from the ring 52, and a slider 54 slidable with respect to the shaft 53 and having one end connected to the piston 4 by a piston pin 44. The rotation center axis of the ring 52 is inclined with respect to the axial direction of the intermediate shaft 23,
When the spherical body 50 rotates together with the intermediate shaft 23, the shaft 53 protruding from the ring 52 swings, and as a result, the piston 4 is driven to reciprocate. The clutch plate 28 constitutes a clutch between the movement converting member 5 and the spherical body 50, and also forms a clutch between the movement conversion member 5 and the pinion 25. That is, a plurality of through holes are provided at the end of the spherical body 50 on the clutch plate 28 side, balls 26 are provided in these through holes, respectively, and a ball is provided on the outer peripheral surface of the intermediate shaft 23. A plurality of engagement recesses 37 into which 26 fits are formed, and a spherical body of the clutch plate 28 is further formed.
The inside diameter of the portion that covers the ball 26 on the 50 side is different in the axial direction. In addition, meshing claws that mesh with each other are provided on the pinion 25 side of the clutch plate 28 and on the clutch plate 28 side of the pinion 25. A switching lever 3 having an operation unit disposed on the outer surface of the housing 11
The eccentric portion is provided with a pin 35 that engages with the outer peripheral rib of the clutch plate 28. In this hammer drill, when in the state shown in FIGS. 1 and 6 (a), that is, when the spring 29 biases the clutch plate 28 toward the pinion 25 side, the pinion
The engagement between 25 and the clutch plate 28 is correct,
When a portion having a large inner diameter of the clutch plate 28 is located on the outer periphery of the ball 26, the rotation of the motor 2 is transmitted from the intermediate shaft 23 to the spindle 31 via the clutch plate 28, the pinion 25 and the like. However, since the intermediate shaft 23 and the reading conversion member 5 are separated from each other, the bit 8 mounted on the chuck 13 rotates only. In this state, when the switching lever 3 is operated to move the clutch plate 28 toward the motion conversion member 5, the clutch plate 28 is moved so that the portion having a small inner diameter is located on the outer periphery of the ball 26, as shown in FIG. Then, the ball 26 is pushed inward. As a result, the ball 26 fits into the engaging recess 27 of the intermediate shaft 23 and connects the intermediate shaft 23 and the spherical body 50. Therefore, the reciprocating motion of the piston 4 is performed through the motion converting member 5, and the reciprocating motion of the piston 4 is caused by the air chamber in the piston 4.
The striking body 41 follows via an air spring at 42, and the striking impact of the striking body 41 hitting the striker 33 is transmitted to the bit 8 through the striker 33. At this point, the bit 8 held by the chuck 13 also rotates because the engagement between the clutch plate 28 and the pinion 25 is still maintained. When the clutch plate 28 is further moved toward the motion conversion member 5 by operating the switching lever 3, the engagement between the clutch plate 28 and the pinion 25 is released as shown in FIG. 2 is no longer transmitted to the spindle 31, so that the bit 8 is only subjected to an axial impact.

【The invention's effect】

As described above, in the present invention, it is possible to selectively cause the bit to rotate only, rotate and hit, and hit only by turning on and off the first clutch means and the second clutch means. Therefore, when performing the hanging operation, only the impact can be applied to the bit, and the workability is improved, and in addition, there is no rotational friction between the bit and the chuck, so that seizure may occur. In addition, the energy loss can be minimized. Moreover, the two clutch means are connected and disconnected by the axial movement of the clutch plate using a single clutch plate to which the rotation of the motor is transmitted as a common clutch element. The first clutch means is disengaged by one-way movement of the clutch plate held at the intermediate position, and the second clutch means is disengaged by the other direction movement of the clutch plate. By simply moving the clutch plate, which is a common clutch element in the means, it is possible to selectively obtain three states of rotation and impact, rotation only, and impact only, without having to be axially movable for switching. The only components which must be replaced are the clutch plates, so that the components involved in the switching, in particular the support configuration, are simplified. It can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, and FIG.
(B) is a partial side view and a sectional view of a drill bit, FIGS. 3 (a) and (b) are partial side views and a sectional view of a hanging bit, FIG. 4 is a perspective view showing the whole of the same, and FIG. 6 (a), 6 (b) and 6 (c) are sectional views showing the operation of the above-mentioned motion conversion member, wherein 2 is a motor, 4 is a piston, 5 is a motion conversion member, and 8 is a motion conversion member. Indicates a drill bit, 28 indicates a clutch plate, 31 indicates a spindle, and 41 indicates a striking body.

Claims (1)

(57) [Claims] 1. A hammer drill comprising a motor, a spindle rotatably driven by the motor and holding a bit, and a hitting portion connected to the motor via a motion converting member to apply a hitting impact to the bit. A first clutch means for controlling power transmission between the motor and the motion conversion member positioned between the motor and the motion conversion member; and a first clutch means positioned between the motor and the spindle for controlling power transmission between the motor and the motion conversion member. The second clutch means controls the power transmission of the motor, and the two clutch means use a single clutch plate to which the rotation of the motor is transmitted as a common clutch element, and can be connected and disconnected by the axial movement of the clutch plate. The first clutch means is disengaged by one-way movement of the clutch plate which holds the connection between the two clutch means at an intermediate position. Hammer drill, characterized in that teeth are made, in which disengagement of the second clutch means in the other direction movement of the clutch plate is made.