JPH02311280A - Hammer drill - Google Patents

Abstract

PURPOSE:To perfectly prevent the idle beating and an abnormal vibration by suppressing the inadvertent operation of a movement conversion member by installing a stopper for regulating the operation of the movement conversion member. CONSTITUTION:A cylindrical body 50 of a movement conversion member 5 is urged towards a clutch 6 side by a spring 29, and in this state, an engaging pin 28 which projectingly installed from the outer peripheral surface of the cylindrical body 50 contacts a stopper 18 which is projectingly installed onto the inner surface of a body housing 1, and the turn of the cylindrical body 50 together with an intermediate shaft 23 is suppressed. Therefore, the generation of idle beating is perfectly prevented, and also the generation of abnormal vibration can be prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a hammer drill in which not only rotation but also axial impact impact can be applied to the drill bit.

[Conventional technology]

There is a tool called a hammer drill as a tool for drilling holes in concrete. This includes a striking means that is reciprocated in the axial direction and a striking body that is also slidable in the axial direction, and an air spring is interposed between the two.
The movement of the striking means is transmitted to the striking body via an air spring, and a striking impact is further applied to the drill bit rotationally driven by the striking body. By the way, if the drill bit is operated without pressing the drill bit against the surface to be drilled, and if impact impact is applied to the drill bit 1, that is, if dry drilling occurs, damage to various parts will be accelerated. In addition, in this type of tool, usually, to prevent dry firing, the striking body does not strike the drill bit when the drill bit is not pressed against the surface to be drilled. Taking the example shown in Japanese Patent Application Laid-Open No. 61-197170, here, a clutch is provided between the motor and a motion converting member that converts the rotational motion of the motor into reciprocating motion.
When the drill bit is pressed against the surface to be drilled, this clutch is engaged, and when the drill bit is released from the surface to be drilled, the clutch is disengaged and the striking means is no longer operated. In other words, the striking means for applying a striking impact to the drill bit is operated only when the drill bit is pressed against the surface to be drilled, thereby preventing dry striking.

[Problem to be solved by the invention]

By the way, the above-mentioned clutch is composed of a pair of a rotating part in the motion converting member and a member on the motor side, and the rotation in the motion converting member is caused by the rotational motion transmitting part connecting the motor and the drill bit. Since the shaft is supported so that it can freely rotate, it has the following problems. In other words, when the drill bit is not pressed against the surface to be drilled and therefore the clutch is disengaged, the rotation of the motor should not be transmitted to the motion converting member at all. In reality, motion conversion is caused by friction between the rotating part of the motion conversion member and the shaft that supports it, and friction between the motion conversion member and the member that restricts the axial movement of the motion conversion member. The members move slowly, which causes slight blanking and abnormal vibrations with slow cycles. This situation becomes more noticeable as the period of use becomes longer and the lubricity between the shaft and the motion converting member is impaired and the frictional resistance increases. However, in order to solve this problem, even in the device disclosed in the above publication, a bearing is arranged between the shaft for transmitting rotational motion and the motion converting member supported by the shaft so as to freely rotate. However, bearings used for converting rotations reaching 3,000 to 4,000 revolutions per minute into reciprocating motion for driving the striking means have a high load capacity because the reaction force during striking is concentrated. This results in an increase in the size of the equipment. 41 The present invention has been made in view of these points, and its purpose is to provide a hammer that can reliably prevent dry striking and abnormal vibrations, and that does not cause the equipment to become larger. There is a drill to offer.

[Means to solve the problem]

Therefore, the present invention includes a motor, a spindle that is rotationally driven by the motor and holds a drill bit, and a spindle that is connected to the motor via a motion converting member to perform reciprocating motion and that is connected to the motor through an air spring and a striking body. In a hammer drill equipped with a striking means that applies a striking impact to a drill bit, and a clutch located between a motor and a motion conversion member to control power transmission between the two, the motion conversion is performed according to the connection state of the clutch. It is characterized by the provision of a stopper that restricts the movement of the member. [Function] According to the present invention, when the clutch is not engaged in order to prevent dry firing, the stopper forcibly stops the rotation of the rotating part of the motion converting member. The rotating part does not rotate together with the shaft. [Examples] The present invention will be described in detail below based on illustrated examples. First, to explain the overall structure, the main body housing 1 has a chuck part 13 on its front end to which the drill bit 8 is attached, and as shown in FIG. 4, a handle part 16 extends from the lower part of the rear end. A storage battery pack 9 is removably extended and is located below the center and in front of the handle portion 16. In the figure, 14 is the switch handle, 1
5 is a rotation direction switching handle. The motor 2 is housed in the rear part of the main body housing 1 with its axial direction being the front-back direction, and a pinion 21 is fixed to the output shaft 20 of the motor 2, as shown in FIG. The gear 24 with which this pinion 21 meshes has bearings 22 and 2 at both ends which are connected to the main body housing 1 and the motor mounting base 12.
The intermediate shaft 23 is press-fitted to one end of an intermediate shaft 23 which is rotatably supported via the motor 2 and whose axial direction is parallel to the axial direction of the motor 2 . The intermediate shaft 23 has a motion converting member 5 attached to the gear 24 side, and a pinion 5 formed on the outer peripheral surface of the other end, and a clutch described later is provided on the outer periphery between the pinion 25 and the motion converting member 5. 6 are arranged. Inside the front end of the main body housing 1, which also serves as a gear case, is a spindle 3 rotatably supported by a bearing 30.
is installed. This spindle 3 has a key 3 having a gear 32 that engages with the pinion 25 on the outer peripheral surface of the rear end.
8 and a retaining ring 39, a striker 33 is disposed inside so as to be slidable in the axial direction, and the tip part allows the drill bit 8 to slide freely within a predetermined range. It constitutes one member of the chuck 13 that holds it in place. Here, the striker 33 has its sliding range in the axial direction restricted by a locking body 34 fixed inside the spindle 3, and the rear end portion having a small diameter has a locking body 34 fixed inside the spindle 3. A cup-shaped clutch bushing 35 housed in the end portion is covered, and an elastic body 37 like a circle ring is disposed between the striker 33 and the clutch bushing 35 in the axial direction. Clutch bush 35 is
A protrusion 36 is provided that protrudes from the rear end opening of the spindle 3. On the other hand, behind the striker 33, a piston 4 having a cylindrical shape with a bottom as a striking means, and a striking body 41 slidably disposed within the piston 4 are installed. The piston 4 is a cylindrical member that is slidably held in a direction parallel to the axial direction of the intermediate shaft 23 and the spindle 3 by a part of a cylinder formed on the motor mount 12 to which the motor 2 is attached. The rear end side connected to the motion converting member 5 is closed. The motion converting member 5 converts rotational motion into reciprocating motion, and is a cylindrical body 5 through which the intermediate shaft 23 is inserted, so that it can freely rotate in reverse relative to the intermediate shaft 23 and can also freely move minutely in the axial direction.
0, a ring 52 rotatably attached to the outer circumferential surface of the cylindrical body 5o via a large number of balls 51, and a ring 5.
The shaft 53 is slidably inserted through the shaft 53 and the spherical outer surface is connected to the joint receiver 55.
It consists of a universal joint 54 rotatably connected to the rear end of the piston 4 via a joint spring 56, which is attached to a shaft 53 and urges the universal joint 54 toward a joint receiver 55. The tip of the shaft 53 passing through the universal joint 54 is located in a long groove 42 formed at the rear end of the piston 4 and extending in the axial direction of the piston 4. The cylindrical body 50 is biased toward the clutch 6 by a spring 29 disposed between the cylindrical body 50 and the gear 24, and has an engagement pin 28 protruding from the outer peripheral surface toward the inner surface of the main body housing 1. There is. In the figure, 81 is a spacer arranged between the spring 29 and the gear 24. The ring 52 in the motion converting member 5 has its rotation center axis inclined with respect to the axial direction of the intermediate shaft 23, so when the cylinder body 50 rotates together with the intermediate shaft 23, the ring 52 does not protrude. The provided shaft 53 swings in a plane that includes both the piston 4 and the intermediate shaft 23, since the rotation around the intermediate shaft 23 is restricted from the screws 1 to 4 side. As a result, the piston 4 is driven back and forth. Next, a description will be given of the clutch 6, which is responsible for transmitting rotation between the intermediate shaft 23 and the cylindrical body 50 of the motion converting member 5, which is freely reversible with respect to the intermediate shaft 23. This clutch 6 includes a cylindrical clutch shaft 6o disposed on the outer periphery of a portion of the intermediate shaft 23 between the pinion 25 and the motion conversion member 5, and a clutch plate 65 disposed on the outer periphery of the clutch shaft 60. and the cylindrical body 50 of the motion converting member 5 is connected to the intermediate shaft 23.
The steel ball 61 is connected to the steel ball 61. The clutch shaft 60 is slidable in the axial direction with respect to the intermediate shaft 23, and a thrust plate 62 and a spring receiver 63 are attached to the pinion 25 side.
A protrusion 64 is formed on the outer peripheral surface of the other end, and the intermediate shaft 23
The pinion 25 is biased toward the pinion 25 by a return spring 75 disposed between the retaining ring 26 and the retaining ring 26 attached to the pinion 25 . The clutch plate 65 is further slidable in the axial direction with respect to the clutch shaft 60, and the clutch plate 65 is configured to be able to freely slide in the axial direction with respect to the clutch shaft 60.
4 on the inner circumferential surface of one end, a retaining ring 69 on the inner circumferential surface of the central part, a flange 67 on the outer circumferential surface, and a protrusion 66 on the inner circumferential surface of the other end on the cylindrical body 50 side. It includes a retracting portion 68 with a larger inner diameter, and is biased toward the motion converting member 5 by a pressing spring 76 disposed between the spring receiver 63 and the spring receiver 63 . The steel balls 61 are respectively disposed in a plurality of holding holes 57 formed at the end of the cylinder 50 located between the inner circumferential surface of the clutch plate 65 and the intermediate shaft 23, and each of the steel balls 61 has a diameter is larger than the wall thickness of the end portion of the cylindrical body 50. A plurality of engagement recesses 27 are provided on the outer peripheral surface of the intermediate shaft 23, with which the steel balls 61 engage when the steel balls 61 move toward the center of the cylinder 50 by being pushed by the clutch plate 65. ing. However, in the lever 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 an advanced position as shown in FIG. Also, at this time, the clutch shaft 60 and the clutch plate 65 are biased by the return spring 75, and the retracted portion 68 of the clutch plate 65 has a large inner diameter.
is located on the outer periphery of the steel ball 61, and the steel ball 61 is located in the retraction part 6.
8, the intermediate shaft 23 and the cylindrical 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 intermediate shaft 23 to the drill bit 8 via the spindle 3, but the motion converting member 5 is not connected to the drill bit 8. In this case, the piston 4 does not reciprocate, and only the drill bit 8 rotates. Further, the cylindrical body 50 of the motion converting member 5 is urged toward the clutch 6 side by the spring 29, and in this state, the engagement pin 28 protruding from the outer peripheral surface of the cylindrical body 50 is As shown in the figure, the cylindrical body 5 is in contact with a stopper 18 protruding from the inner surface of the main body housing 1.
Even if the shaft 0 tries to rotate together with the intermediate shaft 23, this is prevented, so there is no chance of blank firing or abnormal vibration. Next, once the tip of the drill bit 8 is pressed against the surface to be drilled, the drill bit 8 is moved backward relative to the spindle 3 within the permitted range, and the striker 33 is moved backward, as shown in FIG. Push this to move it backwards. The striker 33 moves the elastic body 37 and the clutch bush 35 rearward, and the protrusion 36 of the clutch bush 35 pushes the clutch shaft 60 through the return spring 75 through the thrust plate 62 and the spring receiver 63. against the movement conversion member 5 side. At this time, the retaining ring 6 provided on the clutch plate 65 moves the cylindrical body 50 of the motion converting member 5 backward by the deflection of the spring 29 against the spring 29. As a result, the clutch plate 65 moves toward the motion converting member 5 side while being biased by the pressing spring 76, and the retracting portion 68
In order to position the part with a smaller inner diameter on the outer periphery of the steel ball 61, the steel ball 61 is pushed inward and
It engages with the engagement recess 27 of. The cylinder 50 holding the steel ball 61 is connected to the intermediate shaft 23 via the steel ball 61. Further, when the cylinder body 50 is retreated by the retaining ring 69, the engagement pin 28 is disengaged from the stopper 18, and the cylinder body 50 is released from its rotation restriction. For this purpose, the piston 4 is thereafter reciprocated through the motion converting member 5, and the striking body 41 follows the reciprocating motion of the piston 4 via the air spring between the inner bottom surface of the piston 4 and the striking body 41. The impact impact when the striking body 41 strikes the striker 33 is transmitted to the drill pit l-8 through the striker 33. When the drilling operation is completed and the drill bit 8 is released from the surface to be drilled, the clutch shaft 60 is returned to its original state by the urging force 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 retraction portion 6 is provided on the outer periphery of the steel ball 61.
8, the steel ball 61 is retracted to the retraction portion 68 and the clutch 6 is disengaged. Furthermore, the clutch push 35, striker 33, and drill pit l-8 return to the state shown in FIG. return. Therefore, the drill bit 8 is in a state where it only rotates. Note that the spring force of the spring 29 is not only smaller than the spring force of the spring 76 provided in the clutch 6, but also has minimum spring characteristics that can press and move the motion converting member 5 in the axial direction. Because of this, this spring 2
The presence of 9 hardly increases the load. spring 29
Instead, as shown in FIG. 5, permanent magnets 82 and 82 are arranged on the opposing surfaces of the spacer 81 and the cylindrical body 50, respectively.
The repulsive force acting between both permanent magnets 82 and 82 may urge the cylindrical body 50 toward the clutch 6, that is, toward the position where the engagement pin 28 engages with the stopper 18. When drilling into iron plates or wood does not need to be accompanied by a blow, as in the case of work, it is sufficient to operate a separation lever 70 shown in FIGS. 3 and 4 provided on the side surface of the main body housing 1. As shown in FIG. 3, the disconnection lever 70 rotatably attached to the main body housing 1 has a pin 71 protruding from an eccentric position on the tip surface, and the movement conversion at the flange 67 of the clutch plate 65 A roller 72 in contact with the surface on the member 5 side is freely rotatably supported by a pin 71, and when the separation lever 70 is rotated,
The roller 72 contacts the surface of the flange 67 on the motion conversion member 5 side, and prevents the clutch plate 65 from moving toward the motion conversion member 5 side. Therefore, even when the clutch bush 35 pushes the clutch shaft 60, the clutch 6 is forcibly prevented from engaging. Also at this time, the stopper 18
Of course, this prevents the rotation of the cylindrical body 50 of the motion converting member 5. Other embodiments are shown in FIGS. 6 and 7. This applies when the clutch 6 is connected and the cylinder body 50 is rotated, and when the clutch 6 is connected and the cylinder 50 is rotated.
This method takes advantage of the fact that the rotational torque is significantly different from the rotation of the cylindrical body 50 due to co-rotation that occurs when the cylindrical body 50 is not connected. A pin-shaped stopper 18 is provided on the housing 1 side and is biased toward the cylindrical body 5° by a spring 84. Then, the engagement force between the stopper 18 and the recess 83 under the biasing force of the spring 84 is set to a level slightly stronger than the weak rotational torque at which the cylindrical body 50 tries to rotate together due to the friction between the cylindrical body 50 and the intermediate shaft 23. As such, the cylinder body 50 is prevented from rotating together, and the cylinder body 50 is allowed to rotate against strong rotational torque when driving the striking means.

【Effect of the invention】

As described above, in the present invention, since the movement of the motion converting member is forcibly stopped by the stopper when the clutch is not engaged, the motion converting member does not move inadvertently at all, and there is no possibility of dry driving. Also, it is possible to completely prevent the occurrence of abnormal vibrations.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the same when the clutch is connected, FIG. 3 is a cross-sectional view of the same, FIG. 4 is a broken side view of the same, and FIG. The figure is a partial vertical cross-sectional view of the other side, FIG. 6 is a vertical cross-sectional view of another embodiment, and FIG. 7 is a cross-sectional view of the same. The motion converting member includes a clutch 6, a drill bit 8, a stopper 18, and a striking body 41.

Claims (1)

[Claims] (1) A motor, a spindle that is rotationally driven by the motor and holds the drill bit, and a spindle that is connected to the motor via a motion conversion member to perform reciprocating motion and that is connected to the drill bit via an air spring and a striking body. A hammer drill equipped with a striking means for applying a striking impact and a clutch located between a motor and a motion converting member to control power transmission between the two, including a stopper for regulating the movement of the motion converting member. A hammer drill characterized by: