JPH0132037B2 - - Google Patents

Description

[Detailed description of the invention] 〔Technical field〕 This invention relates to a vibrating drill.

[Background technology]

Conventionally, vibratory drills include the piston hammer type shown in Fig. 1 (Japanese Patent Publication No. 1983-46761),
The ratchet type shown in Figure 2 (Japanese Unexamined Patent Publication No. 1983-53383)
No. 2) has been proposed.

The piston hammer type shown in Figure 1 has a motor 1.
The rotation of the piston 4 is converted from the eccentric camshaft 2 to the reciprocating motion of the piston 4 by the connecting rod 3.
transmits reciprocating motion to the free hammer 6 via the air chamber 5, and the free hammer 6 applies a blow to the bottom of the bit 7. On the other hand, due to other mechanisms,
Rotation is transmitted from the same motor 1 to bit 7,
Bit 7 makes a hole in rock or concrete by the action of so-called rotary impact. The disadvantage of this type is that unless the air chamber 5 is sealed, the reciprocating energy of the piston 4 will not be efficiently transmitted to the free hammer 6, so the air chamber 5 must be hermetically sealed during movement. In the example shown in this figure, the seal 8 of the piston 4 and the seal 9 of the free hammer 6 are
fulfills this function. However, during operation,
In particular, just before the free hammer 6 hits the bit 7, the pressure in the air chamber 5 becomes extremely large (in the literature,
It is said that it can reach up to 2000Kg/cm ² ), Seal 8,
Air will leak unless the tension on 9 (usually the O-ring) is made very strong. Therefore,
In order to smoothly drive the piston 4 and free hammer 6, a large amount of power is required to overcome the frictional force with the cylinder due to the tension force, and the motor 1 must also be large and have a high output. Usually, the power consumption is 400W or more. Moreover, there is a problem in that heat is generated due to friction between the piston 4 and the cylinder. In addition, the reliability of sliding parts,
Particularly, oil lubrication is necessary to improve the lifespan, and the sealing mechanism for this becomes complicated, and together with the aforementioned large motor, it tends to be large and heavy, and it is not easy to use.

In the case of the ratchet type shown in FIG. 2, the rotation of the motor 11 is decelerated by the pinion 12 and the reduction gear 13 to rotate the ratchet plate 14, which is then connected to a ratchet of the same shape that is non-rotatably fixed at an opposing position. The bit is engaged with the plate 15 by the force of pressing it against the material, giving a slight vibration to the output shaft 16, and the vibration and rotational force are used to make a hole in rock or concrete.

This format has the following drawbacks. Unlike the piston hammer method, the striking force is weak because it uses minute vibrations instead of striking force. According to measurements, it is 1/3 to 1/4 of the hammer method. Therefore, it is possible to drill holes in walls that do not contain aggregates such as mortar, but in the case of concrete that contains aggregates (small pieces of rock), the drilling is only possible little by little due to insufficient force, and the drilling time becomes extremely long. become longer. Also, if you increase the motor power and use a vibration drill of about 1KW, you can drill holes even if it hits the aggregate, but the main unit weighs about 5 to 6Kg, making it a very difficult tool to use. I become confused. When drilling a hole, the reaction force of minute vibrations from the bit is transmitted to the hand through the fixed ratchet plate 15, making the hand numb and making it difficult to work for a long time. If an attempt is made to make a hole faster by increasing the micro-vibration impact force, it is necessary to press the fixed ratchet plate 15, which receives the reaction force, more strongly toward the bit. In other words, the hole will not be made unless you press the main body strongly with your hand. With this, for example, drilling a hole in the ceiling, etc.
It is very difficult to perform drilling work in places where the footing is unstable, making it inconvenient for workers to use. Furthermore, the stronger you press, the less the damping effect of your hands becomes, and the more vibrations are transmitted to your body.
It has become impractical.

[Purpose of the invention]

The object of the present invention is to provide a vibration drill which is small in size, can efficiently deliver a large impact, has a simple structure, does not have the problem of heat generation, and does not cause fatigue because the vibrations are not easily transmitted to the hands.

[Disclosure of the invention]

The vibration drill of the present invention includes a motor, an output shaft to which rotation is transmitted from the motor, a hammer that strikes the output shaft, a spring that urges the hammer toward the output shaft, and a vibration drill that is driven by the motor. and a cam mechanism that moves the hammer against the spring and releases the hammer at a predetermined position.

Since the striking force is obtained by the repulsive force of the spring, there is no need to press strongly by hand. In addition, the spring absorbs the shock of the blow, preventing vibrations from being transmitted to your hands.

Embodiment An embodiment of the present invention is shown in FIGS. 3 to 6. In the figure, 20 is a main body, which has a handle 21 and a battery storage part 22. Motor 23 on handle 21
A switch 24 is provided. A motor 23, a cam cylinder 25, a hammer 26, and an output shaft 27 are arranged coaxially within the main body 20. A bit 28 is attached to the part of the output shaft 27 that protrudes from the main body 20.
A chuck 29 is provided for attaching. The output shaft 27 is supported by a bearing 30 at the tip of the main body 20 so as to be rotatable and movable in the axial direction. motor 23
The rotation is decelerated and transmitted to the drive shaft 32 via the planetary gear mechanism 31. A pinion 33 for transmitting rotation to the bit 28 is fixed in the middle of the drive shaft 32 by press-fitting or the like, and a sliding pin 34 that contacts the cam surface of the cam cylinder 25 is fixed at the tip. Sliding pin 3
4 may be one in which a roller is fitted onto the outside. pinion 3
3 meshes with a gear 36 at one end of a transmission shaft 35 provided parallel to the output shaft 27, and transmits rotation to the output shaft 27 via a pinion 37 and a reduction gear 38 at the other end. The reduction gear 38 and the output shaft 27 are the output shaft 2
7 vibrates in the thrust direction, so they are connected by splines.

The hammer 26 is formed into a round shaft shape having an enlarged diameter portion 26a at its tip, and is inserted into a guide cylinder 39 fixed to the rear end of the output shaft 27 so as to be freely movable in the axial direction. A hammer 26 is attached to an output shaft 27 within the guide tube 39.
A spring 40 that urges the guide tube 39 toward the side is housed therein.
A cushion 41 is provided on the inner surface of the end wall at the tip. The cam cylinder 25 is fixed to the rear end of the hammer 26. The cam cylinder 25 serves as a driver. The cam cylinder 25 includes an outer cylinder 25A and a cam member 25.
B, and both are connected with a sear pin or the like.

Operation The rotation of the motor 23 is decelerated by the planetary gear mechanism 31 and transmitted to the drive shaft 32, and is transmitted from the pinion 33 of the drive shaft 32 to the output shaft 27 via the gear 36, transmission shaft 35, pinion 37, and reduction gear 38. transmitted to. In addition, a sliding shaft 34 at the tip of the drive shaft 32
As the drive shaft 32 rotates, the cam surface of the cam cylinder 25 moves as shown in FIG.
Make it reciprocate against zero. The cam cylinder 25 is the hammer 2
6 toward the motor 23, the spring 4
0 is deflected to store energy in the spring 40.
When the sliding shaft 34 passes the top of the cam surface, the energy of the spring 40 causes the hammer 26 to move onto the output shaft 34.
Collision with 7. Therefore, the output shaft 27 performs a motion that combines rotation and impact. The conversion formula for converting the energy stored in the spring 40 into the kinetic energy of the hammer 26 is as follows.

1/2 kx ² = 1/2 mv ² where k: spring constant, v: maximum speed of the hammer, x: maximum displacement, m: mass of the hammer (addition of the mass of the cam cylinder). The impact force when the hammer 26, given the speed v, collides with the output shaft 27 is expressed by the following equation.

f=mv/t Here, f: impact force, t: impact time.

In this way, since energy is stored in the spring 40 to obtain a striking force, there is no need to push the main body 20 strongly by hand, and the work can be easily performed even in a place with poor footing such as a ceiling. Furthermore, since the impact force is obtained using the energy stored in the spring 40, the impact force is large even if the motor 23 is small, and even aggregate in concrete can be crushed. Moreover, since the impact of the bit 28 is transmitted to the main body 20 via the spring 40, the vibration is less likely to be transmitted to the hands and the user does not get tired. Further, unlike the conventional piston hammer type, there is no problem of creating resistance such as friction in order to obtain sealing performance. Therefore, it has the advantage that it is efficient, has a simple structure since no sealing structure is required, and does not generate heat due to friction.

Furthermore, as can be seen from the above equation, the hammer 26
Since the cam cylinder 25 is integrated with the cam cylinder 25, the mass increases and the impact force increases. Therefore, it can be made small and have a large impact force. Further, by utilizing the resonance of the spring 40, the impact force of the hammer 26 can be significantly increased. At this time, the number of blows is set to a value approximately equal to the frequency expressed by the following formula.

f=1/2π√ Here, f: frequency (Hz), π: pi.

6 to 8 show other embodiments. A rotary cylinder 46 is rotatably installed within the fixed cylinder 45 with a bearing 47, and a hammer 26' is fitted into the rotary cylinder 46. The fixed cylinder 45 is fixed to the main body 20 via a mounting member 48 at a cylinder cap portion 45a. The rotating cylinder 46 is connected to the drive shaft 32 by a joint 49. hammer 2
6' also serves as a driver, and has a cam groove 50 on its outer circumferential surface. A sliding pin 51 fixed to the rotating cylinder 46 engages with the cam groove 50 . The hammer 26' has an enlarged diameter portion 26a' on the outer periphery of the tip, and is urged toward the tip of the output shaft 27' by a spring 40' provided between the rotary cylinder 46 and the enlarged diameter portion 26a'. Further, the hammer 26' has a recess 52 in the center, into which the rear end of the output shaft 27' is fitted so as to be movable in the axial direction. The recess 52 has an air hole 53. A cushion 41' is provided on the inner surface of the cylinder cap portion 45a of the fixed cylinder 45, and an air hole 54 is provided in the peripheral wall slightly closer to the motor 23 than the cushion 41'. Further, an air hole 55 is also provided in a portion of the fixed cylinder 45 that corresponds to the periphery of the hammer 26'.

With this configuration, since the recess 52 is provided in the hammer 26' to accommodate a part of the output shaft 27', the hammer 26' and the output shaft 27' overlap in the length direction, and the overall shape is reduced by that much. The length of can be shortened. Therefore, when the main body 20 is held by hand, the distance between the handle 21 and the tip of the bit 28 is shortened, improving usability. Further, as in the embodiment described above, since the cam portion is integrally provided with the hammer 26', the mass of the hammer 26' can be increased.
You can increase your hitting power.

Expanded diameter portion 2 of hammer 26' of fixed cylinder 45
6a' and the output shaft 27' and hammer 2.
It is desirable that the fitting portion of 6' with the recess 52 be tightly fitted for smooth operation. If this is done, air pockets will occur and movement resistance will occur, but the air holes 53 to 55 will be placed in each air pocket.
This resistance can be eliminated. Therefore, a decrease in efficiency can be prevented, and the motor 23
It is possible to reduce the size and weight of batteries.

In addition, the impact against blank firing of the hammer 26' can be alleviated as follows. Hammer 26' is output shaft 2
7' and when drilling a hole, the kinetic energy is weakened by the impact and the cylinder cap 45a
The hammer 26' hits. Therefore, there is no damage to the cylinder cap 45a. However, during dry firing, the hammer 26' directly hits the cylinder cap 45a.
Since the kinetic energy is large, the damage will be large if left as is. In order to solve this problem, the air hole 54 is positioned closer to the hammer 26' by an amount Q than the front surface of the cushion 41', as shown in FIG. Hammer 26' is attached to cylinder cap 4
5a, the air in the space 56 (FIG. 8) is released from the air hole 54. At this time, cushioning action can be obtained by the cushion 41' of the cylinder cap 45a, but this alone is not sufficient for the cushion 41'.
It cannot perform its function unless 1' is made very large. However, if the air hole 54 is arranged as described above, when the hammer 26' approaches the cylinder cap 45a until it passes through the air hole 54, there is no place for the remaining air to escape, and it acts as an air spring. Therefore, the buffering function of the hammer 26' is improved. Thereby, the cushion 41' can be made smaller, and the overall length can be shortened accordingly. The rest is the same as the first embodiment.

〔Effect of the invention〕

Since the vibrating drill of the present invention applies a striking force using the biasing force of a spring, there is no need to forcefully press it by hand, and the spring absorbs the impact of the striking, so that vibrations are not transmitted to the hands. Therefore, workers do not get tired.
Furthermore, by driving the motor, deflection energy is stored in the spring via the cam mechanism, and the cam mechanism releases the hammer, thereby obtaining the striking force from the deflection energy of the spring, so it is not based on air pressure. Unlike this, it does not require a sealed structure and has a simple structure. Moreover, there is no problem of heat generation due to piston friction. Furthermore, since striking and rotation are performed by one motor, the structure is simple.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional example, FIG. 2 is a sectional view of another conventional example, FIG. 3 is a sectional view of an embodiment of the present invention, and FIG. 4 is a partial sectional view of its different operating states.
5A to 5C are diagrams illustrating its operation, FIG. 6 is a sectional view of another embodiment, FIGS. 7A and B are diagrams illustrating its operation, and FIG. 8 is a partially enlarged sectional view thereof. 20...Main body, 23...Motor, 25...Cam cylinder (driver), 26, 26'...Hammer, 27, 2
7'... Output shaft, 28... Bit, 31... Planetary gear mechanism, 32... Drive shaft, 34... Sliding shaft, 3
9... Guide tube, 40, 40'... Spring, 41,
41'...Cushion, 45...Fixed cylinder,
46...Rotating cylinder, 50...Cam groove, 53~
55...Air hole.

Claims (1)

[Scope of Claims] 1. A motor, an output shaft to which rotation is transmitted from the motor, a hammer that strikes the output shaft, a spring that biases the hammer toward the output shaft, and a spring driven by the motor. a cam mechanism that moves the hammer against the spring and releases the hammer at a predetermined position. 2. The vibration drill according to claim 1, wherein a recess is provided in the center of the hammer, and the rear end of the output shaft is accommodated in the recess so as to be movable in the axial direction. 3. The vibratory drill according to claim 1, further comprising: a cylinder fitted onto the hammer to support the hammer so as to be movable in the axial direction; and an air hole provided in the cylinder. 4. A cushion is provided on the inner surface of the end wall of the cylinder facing the front surface of the hammer, and the air hole is located at a position slightly farther from the inner surface of the end wall than the front end surface of the cushion. Vibration drill as described in section.