JPH0653327B2 - Hammer drill - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hammer drill in which not only rotation but also impact impact in the axial direction is applied to a drill bit.

[Prior art]

As a tool for drilling holes in concrete, there is a tool called a hammer drill. This is provided with a striking means that is reciprocally driven in the axial direction and a striking body that is also slidable in the axial direction, and if the striking means transmits its movement to the striking body, the striking body is rotated in the drill bit. Further, a striking impact is applied. By the way, if the impact is applied to the drill bit even when the drill bit is not pressed against the surface to be drilled, that is, if the drill bit occurs, each part will be damaged quickly, In this kind of tool, as a prevention of blank hitting, the hitting body is prevented from hitting the drill bit by means such as limiting the movement of the hitting body when the drill bit is not pressed against the surface to be drilled. Although it is configured, since the striking means was still reciprocally driven, damage due to idle driving can be prevented, but there is a problem that energy consumption is large and noise is generated. . In particular, the consumption of energy becomes a serious problem in the case of using a battery as a power source. For this reason, British Published Patent No. 2,170,746 shows the following. This is because a clutch is provided between the striking means and the motor, and the clutch is connected when the drill bit is pressed against the surface to be drilled, and when the drill bit is separated from the surface to be drilled, the clutch is disengaged and the striking means is activated. I try not to do it. In other words, while holding the drill bit, the spindle transmitting the rotational force from the motor to the drill bit is made slidable in the axial direction, and the retracting of the spindle when the drill bit is pressed against the surface to be drilled is used. Thus, the clutch is connected, and the striking means for giving a striking impact to the drill bit is operated only when the drill bit is pressed against the surface to be drilled.

[Problems to be Solved by the Invention]

By the way, in a hammer drill provided with a clutch capable of disconnecting the power transmission to the striking means, including the above-mentioned conventional example, the clutch transmits the power transmission by moving a required member in the axial direction of the drill bit. Since it was a disengagement, the reaction of the impact of the impact at the time of perforation is transmitted to the clutch, and the reaction also causes a slight vibration in the engagement and disengagement direction, making the clutch connection state unstable. There is also a problem that an abnormal sound is generated. In the above-mentioned conventional example, since the axial movement of the drill bit is directly transmitted to the clutch to cause the clutch to make an on / off operation, it is even more susceptible to vibration. The present invention has been made in view of such a point, and an object thereof is to stabilize the clutch connection state without becoming unstable due to the reaction of the impact at the time of punching and without generating abnormal noise. The purpose of the present invention is to provide a hammer drill in which the connected state is maintained and the clutch can be forcibly disengaged.

[Means for Solving the Problems]

Therefore, the present invention provides a motor, a spindle that is driven to rotate by the motor and holds a drill bit, and a motor that is connected to the motor through a motion conversion member to reciprocate and to a drill bit through an impacting body. A hammer bit comprising a hammering means for applying a hammering impact in the axial direction and a clutch for controlling power transmission to a motion converting member located in a rotation transmitting part from a motor to a motion converting member. Is movable in the axial direction, and the clutch moves in the axial direction along with the movement of the drill bit to open and close the connected state, and the engaging portion provided on the clutch plate responds to an external operation. And an operation mode switching stopper that prevents movement of the clutch plate for coupling the clutch at the time of engagement. A pressing spring is interposed between the latch plate and the clutch push for transmitting the backward movement of the drill bit to the clutch plate, and the backward movement of the drill bit is transmitted to the clutch plate through the pressing spring. is doing. As such a clutch, the drive shaft on the motor side, the engagement portion on the motion conversion member side concentric with the drive shaft, the drive shaft by moving in the direction orthogonal to the axial direction of the drive shaft and the engagement portion, The drive shaft and the engaging portion are provided with a connecting member that connects the engaging portion and a clutch plate that is located on the outer peripheral side of the connecting member and that moves the connecting member by movement in the drive shaft direction accompanying movement of the drill bit. A connecting member held by a member located on the outer peripheral side of the engaging member engages with an engaging recess formed on the outer peripheral surface of the member located on the inner peripheral side to connect the drive shaft and the engaging portion, It is possible to use a member that releases the linkage by releasing the connecting member from the engaging recess. [Operation] According to the present invention, the striking means also does not operate when the striking vibration is not applied to the drill bit, and the recoil of the striking impact given to the drill bit when the striking means is activated is Since it is absorbed by the pressure spring that is interposed between the clutch plate and the clutch plate, the clutch is not affected by the reaction of the impact to the drill bit, that is, the vibration of the drill bit in the axial direction. By using the stopper for switching the operation mode, which can be engaged and disengaged with the clutch plate in response to an external operation and prevents the clutch plate from moving for engaging the clutch when engaged, forcing impact It is also possible to separate them. [Examples] The present invention will be described below in detail based on illustrated examples. First, the overall structure will be described. In the main body housing 1, a chuck 13 to which the drill bit 8 is attached is arranged at a front end thereof, and a handle portion 16 is extended from a lower portion of a rear end thereof, and a lower portion of a central portion is provided. The storage battery pack 9 is detachably attached to the front of the handle portion 16. In the figure, 14 is a switch handle and 15 is a rotation direction switching handle. The motor 2 is housed in the rear portion of the main body housing 1 with its axial direction in the front-rear direction, and a pinion 21 is fixed to its output shaft 20 as shown in FIG.
The gear 24 meshing with the pinion 21 has both ends rotatably supported by the housing 1 and the motor mount 12 via bearings 22 and 22, and has an axial direction parallel to the axial direction of the motor 2. It is press-fitted and fixed to one end of. The drive shaft 23 has a motion converting member 5 attached to the gear 24 side and a pinion 25 formed on the outer peripheral surface on the other end side. A clutch to be described later is provided on the outer periphery between the pinion 25 and the motion converting member 5. 6 are provided. A spindle 3 rotatably supported by a bearing 30 is installed in a front end portion of the main body housing 1 which also serves as a gear case. The spindle 3 has a gear 32 that meshes with the pinion 25 fixed to the outer peripheral surface of the rear end of the spindle 3 by a key 38 and a retaining ring 39.
A striker 33 is provided inside so as to be slidable in the axial direction, and the tip end portion thereof is one component of the chuck 13. The chuck 13 holds the drill bit 8 so that it can be slid within a predetermined range by engaging an engaging body 81 with a groove 80 formed in the outer peripheral surface of the drill bit 8 and extending in the axial direction. The attachment / detachment of the drill bit 8 is performed by rotating the ring 82 positioned on the outer periphery of the engagement body 81 and retracting the engagement body 81 into the recess 83 formed in the inner peripheral surface of the ring 82. The striker 33 has an axial sliding range restricted by a locking body 34 fixed to the inside of the spindle 3, and an elastic body such as an O-ring is formed at the rear end portion having a small diameter. 37 and a cup-shaped clutch push 35 housed in the rear end of the spindle 3 are covered.
The elastic body 37 is located between the striker 33 and the clutch push 35 in the time direction. Further, the clutch push 35 is provided with the protrusion 3 protruding from the rear end opening of the spindle 3.
6 is provided. On the other hand, behind the striker 33, a piston 4 as a hitting means having a bottomed cylindrical shape, and a hitting body 41 slidably arranged in the piston 4 are installed. The piston 4 located axially rearward of the spindle 3 is slidable in a direction parallel to the axial direction of the drive shaft 23 and the spindle 3 by the cylinder portion formed on the motor mounting base 12 to which the motor 2 is mounted. Is held in
The rear end side connected to the motion converting member 5 is closed. The sliding direction of the impacting body 41 is the piston 4
In the same direction as. The motion converting member 5 converts the rotational motion transmitted through the drive shaft 23 into a reciprocating motion, and has a large number on the outer peripheral surface of the tubular body 50 in which the drive shaft 23 is inserted and the inner race fixed to the tubular body 50. An outer race 52 rotatably attached via individual balls 51, a shaft 53 projecting from the outer race 52, and a shaft 53 slidably inserted and made spherical. A universal joint 54 whose outer surface is rotatably connected to the rear end of the piston 4 via a joint receiver 55, and a universal joint 5 mounted on a shaft 53.
4 and a joint spring 56 that biases the joint 4 toward the joint receiver 55. The tip of the shaft 53 passing through the universal joint 54 is long in the axial direction of the piston 4 formed at the rear end of the piston 4. It is located in the long groove 42. The outer race 52 of the motion converting member 5 has a center axis of rotation inclined with respect to the axial direction of the drive shaft 23. Therefore, when the tubular body 50 rotates together with the drive shaft 23, the outer race 52. Shaft 53 protruding from
Since the rotation around the drive shaft 23 is restricted from the piston 4 side, the rocking is performed in a plane including both the piston 4 and the drive shaft 23 as shown in FIG. As a result, the piston 4 is reciprocally driven. Next, the clutch 6 that turns on / off the rotation transmission between the drive shaft 23 and the cylindrical body 50 of the motion converting member 5 that is freely rotatable with respect to the drive shaft 23 will be described. The clutch 6 has a cylindrical clutch shaft 60 arranged on the outer circumference of a portion of the drive shaft 23 between the pinion 25 and the motion converting member 5, and a clutch plate 65 arranged on the outer circumference of the clutch shaft 60. And a steel ball 61 that connects the tubular body 50 of the motion converting member 5 to the drive shaft 23 that is coaxial with the tubular body 50. The clutch shaft 60 is slidable in the axial direction with respect to the drive shaft 23. A thrust plate 62 and a spring receiver 63 are attached to the pinion 25 side of the clutch shaft 60, and a protrusion is provided on the outer peripheral surface of the other end. The portion 64 is formed and is urged toward the pinion 25 side by a return spring 75 arranged between the portion 64 and the retaining ring 26 attached to the drive shaft 23. The clutch plate 65 is further slidable in the axial direction with respect to the clutch shaft 60.
4, a protrusion 66 that engages with 4 is provided on one inner peripheral surface, a flange 67 is provided on the outer peripheral surface, and a retracting portion 68 having a larger inner diameter is provided on the other inner peripheral surface on the side of the tubular body 50. By the pressing spring 76 arranged between the spring receiver 63 and
It is biased toward the motion converting member 5 side. The steel balls 61 are respectively arranged in a plurality of holding holes 57 formed at the end portion of the tubular body 50 located between the inner peripheral surface of the clutch plate 65 and the drive shaft 23, and the diameter thereof. Is larger than the wall thickness of the end of the tubular body 50. A plurality of engagement recesses 27 are provided on the outer peripheral surface of the drive shaft 23. The engagement recesses 27 engage the steel ball 61 when the steel ball 61 moves toward the center of the drive shaft 23 by being pushed by the clutch plate 65. ing. However, in this hammer drill, when the tip of the drill bit 8 is not in contact with the surface to be drilled, the striker 33 is in the advanced position as shown in FIG. At this time, the retracting portion 6 having a large inner diameter of the clutch plate 65 is urged by the return spring 75 to urge the clutch shaft 60 and the clutch plate 65.
8 is located on the outer periphery of the steel ball 61, and the steel ball 61 is pushed by the outer peripheral surface of the drive shaft 23 by the centrifugal force due to the rotation of the drive shaft 23 and is allowed to be retracted to the retreat portion 68. The shaft 23 and the tubular body 50 are in a separated state. Therefore,
When the motor 2 is operated by operating the switch handle 14, the rotation of the motor 2 is transmitted from the drive shaft 23 to the drill bit 8 via the spindle 3, but the motion converting member 5 is separated, The piston 4 does not reciprocate, only the drill bit 8 rotates. In this state, if the tip of the drill bit 8 is pressed against the surface to be drilled, as shown in FIG. 2, the drill bit 8 moves backward relative to the spindle 3 (retracts, the striker 33 The striker 33 moves the elastic body 37 and the clutch push 35 rearward, and the protrusion 36 of the clutch push 35 causes the thrust plate 62 and the spring receiver 6 to move.
3, the clutch shaft 60 is pushed against the return spring 75 toward the motion converting member 5. As a result, the clutch plate 65 moves to the motion converting member 5 side while being biased by the pressing spring 76, and the retracting portion 68.
In order to locate a portion having an inner diameter smaller than the outer peripheral portion of the steel ball 61, the steel ball 61 is extruded inward and the drive shaft 23
Engages with the engaging recess 27. The tubular body 50 holding the steel ball 61 in the holding hole 57 is connected to the drive shaft 23 via the steel ball 61.
The rotation of the drive shaft 23 is transmitted to the motion converting member 5 by being connected to. For this reason, hereinafter, the motion converting member 5
When the striking body 41 follows the reciprocating movement of the piston 4 through the air spring between the inner bottom surface of the piston 4 and the striking body 41, and the striking body 41 strikes the striker 33. Of the impact is transmitted to the drill bit 8 through the striker 33. Here, the axial vibration due to the reaction when the impact impact is applied to the drill bit 8 is absorbed by the pressing spring 76 arranged between the clutch shaft 60 and the clutch plate 65, and also the striker 33 and the clutch push. Since it is also absorbed by the elastic body 37 arranged between the clutch 35 and the clutch 35, it is hardly transmitted to the clutch plate 65. Therefore, the connected state of the clutch 6 becomes unstable, and abnormal noise is generated. It does not occur. In addition, since the power transmission between the drive shaft 23 and the motion converting member 5 is turned on and off by moving the steel ball 61 in the direction orthogonal to the axial direction of the drill bit 8, the impact shock is drilled. Even if the axial vibration due to the reaction when applied to the bit 8 is transmitted to the clutch plate 65 and the like, the connection between the drive shaft 23 and the tubular body 50 by the steel ball 61 of the clutch 6 is a distance indicated by α in FIG. If the clutch plate 65 does not move, the state of the clutch plate 65 does not change at all. Therefore, the minute axial movement of the clutch plate 65, which is caused by the axial vibration, has no influence on the connection state and is stable. Maintained in a state. When the drilling work is completed and the drill bit 8 is separated from the surface to be drilled, the clutch shaft 60 is returned by the bias of the return spring 75, and the clutch plate 65 is also pulled by the clutch shaft 60 and separated from the motion converting member 5. A retracting portion 6 is provided on the outer peripheral portion of the steel ball 61.
In order to position 8, the steel ball 61 is pushed out by the outer peripheral surface of the drive shaft 23 and retracts to the retracting portion 68, and the clutch 6 is disengaged. The clutch push 35, the striker 33, and the drill bit 8 also return to the state shown in FIG. Therefore, the drill bit 8 is in a state of only rotating. When it is not necessary to hit with a hammer such as when punching a steel plate or wood, the disconnecting lever 70 shown in FIGS. 4 and 5 provided on the side surface of the main body housing 1 may be operated. The detaching lever 70 rotatably attached to the main body housing 1 is provided with a pin 7 from the eccentric position of the tip surface.
1 is projected, and a roller 72 which is in contact with the surface of the flange 67 of the clutch plate 65 on the side of the motion converting member 5 is rotatably supported by the pin 71, and the clutch plate 6
5, which constitutes an operation mode switching stopper that restricts or allows the forward and backward movements of 5, and the release lever 70
When the clutch shaft 65 is rotated, as shown in FIG. 3, the roller 72 comes into contact with the flange 67, and even when the clutch shaft 60 is moved toward the motion converting member 5, the clutch plate 65 is compressed while the pressing spring 76 is compressed. Are prevented from moving to the motion converting member 5 side. Therefore, as shown in the figure, even when the clutch push 35 pushes the clutch shaft 60,
It is possible to forcibly prevent the clutch 6 from entering and to bring the drill bit 8 into a state in which only rotation is given.

【The invention's effect】

As described above, in the present invention, the striking means does not operate when the striking vibration is not applied to the drill bit, so that not only the blank striking can be prevented, but also energy consumption and noise generation are small, and striking The reaction of the impact shock given to the drill bit when the means is operated is absorbed by the pressure spring interposed between the drill bit and the clutch plate, so that the reaction of the impact against the drill bit, that is, the drill. The clutch is not affected by the vibration of the bit in the axial direction, and therefore, the clutch maintains a stable connected state and does not generate an abnormal sound, and has good operating characteristics. There is.
Moreover, since the operation plate is provided with an operation mode switching stopper that can be disengaged from the clutch plate in response to an external operation and that prevents the clutch plate from moving for engaging the clutch when engaged, forcibly disconnecting the striking means. It is also possible to select an operation mode suitable for various various works, and in particular, forcibly disconnecting the striking means can utilize the existence of the pressing spring, so that it is easy to perform. It can be realized by a structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view when the above clutch is connected, and FIG. 3 is a vertical cross-sectional view when the above clutch is forcibly disengaged. , Fig. 4 is a cutaway side view of the same as above.
FIG. 5 is a transverse cross-sectional view of the above, wherein 2 is a motor, 3 is a spindle, 4 is a piston, 5 is a motion converting member, 6 is a clutch, 8 is a drill bit, 23 is a drive shaft, and 27 is an engaging recess. , 35 is a clutch push, 41 is a hitting body, 60 is a clutch shaft, 61 is a steel ball, 65 is a clutch plate, and 76 is a pressing spring.

Claims (2)

[Claims] 1. A motor, a spindle which is rotationally driven by the motor and holds a drill bit, and a motor which is connected to the motor through a motion converting member to reciprocate and to the drill bit through an impacting body. In a hammer drill equipped with a striking means for applying a striking impact in the axial direction and a clutch for controlling power transmission to the motion conversion member, which is located in the rotation transmission part from the motor to the motion conversion member, the drill bit is The clutch is movable in the axial direction, and the clutch moves in the axial direction with the movement of the drill bit to open and close the connected state, and the engaging portion provided on the clutch plate responds to an external operation. The clutch is provided with an operation mode switching stopper that can be disengaged and that prevents movement of the clutch plate for engaging the clutch when engaged. A pressing spring is interposed between the plate and the clutch push for transmitting the backward movement of the drill bit to the clutch plate, and the backward movement of the drill bit is transmitted to the clutch plate through the pressing spring. Hammer drill. 2. The clutch comprises a drive shaft on the motor side, an engaging portion on the side of the motion converting member which is concentric with the drive shaft, and a drive shaft which moves in a direction orthogonal to the axial direction of the drive shaft and the engaging portion. And a clutch plate that is located on the outer peripheral side of the connecting member and that moves the connecting member by movement in the drive shaft direction accompanying the movement of the drill bit, and engages with the drive shaft. The connecting member held by the member located on the outer peripheral side of the part engages with the engaging recess formed on the outer peripheral surface of the member located on the inner peripheral side to connect the drive shaft and the engaging part. The hammer drill according to claim 1, wherein the connection member is released by releasing the connection member from the engagement recess.