JPS6210764B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a vibratory drill that increases impact force and reduces operator fatigue. (Background Art) When drilling into hard and brittle materials such as concrete, simply applying weight to the drill bit and applying rotation to it is inefficient, so a method of repeatedly applying impact force to the rotating shaft is used. FIG. 1 shows the configuration of a conventional vibratory drill, with main parts shown in cross-section. 1 is the drill body;
The drill body 1 mainly includes a body housing 2 and a vibration housing 3. Reference numeral 4 denotes a rotating shaft, at the tip of which a drill bit 6 is mounted by a chuck 5, and the rotating shaft 4 is rotatably attached to the drill body 1 by bearings 7 and 8. The bearings 7 and 8 are loosely fitted on either the rotating shaft side or the drill body side, so that the rotating shaft 4 can also slide in the axial direction. Further, reference numeral 9 denotes a motor, which provides rotation to the rotating shaft 4 via a pinion 10 and a reduction gear 11. On the other hand, 12 and 13 are a pair of diaphragms,
The first diaphragm 12 is fixed to a vibration housing 3 that is a part of the drill body 1 and is slidably fitted to the diaphragm 4, and the second diaphragm 13 is fixed to the rotating plate 4. Due to the repulsive force of the spring 14, the two diaphragms 12 and 13 are normally spaced apart from each other in the axial direction and face each other. The diaphragms 12 and 13 are disk-shaped as shown in FIG. 2, and one end surface of the diaphragms 12 and 13 is provided with continuous unevenness in the circumferential direction, and as shown in FIG. As a result, displacement corresponding to the difference in unevenness _δ1 is repeatedly generated in the axial direction.
Further, in FIG. 1, 15 is a power switch, and 16 is a power cord. In operation, when the power switch is turned on, the motor 9 rotates, and the pinion 10 and reduction gear 11
Rotational power is applied to the rotating shaft 4 via the rotary shaft 4. In this state, when the drill bit 6 is applied to a material such as a concrete wall and the drill body 1 is pressed, the rotary shaft 4 slides toward the body (to the left in the figure) against the repulsive force of the spring 14, and the first and second Vibration plate 1
2 and 13 will come into contact and engage. Since the first diaphragm 12 is fixed to the main body, vibrations in the axial direction are applied to the rotating shaft 4 due to the collision and running of the crests of the diaphragms 12 and 13 as they rotate. When the vibration width is δ ₁ and the spring constant of the spring 14 is K ₁ , the energy expressed as E ₁ = 1/2K ₁ δ ₁ ² ......(1) is stored in the spring 14 for each vibration. , each time the drill bit 6 is ejected as a force to push it toward the front of the main body, giving an impact force. By the way, in the conventional vibration drill mentioned above, the impact energy is given by the above equation (1), and the spring constant K ₁ is determined within the range that can be held down by hand, so the energy E ₁ is relatively small. However, compared to other impact tools, such as the well-known hammer drill, the impact force is weaker, making it more time-consuming to drill holes, and requiring the drill body to be pressed strongly against the material, resulting in work problems. In addition to being tiring, the vibrations are strongly transmitted to the hands, and the long working hours make them susceptible to so-called vibration disease. In addition, if the vibration width δ ₁ is increased in an attempt to increase the energy E ₁ in order to improve the above-mentioned drawbacks, that is, the difference in the unevenness of the diaphragm is made too large, the load on the diaphragm becomes excessive, and the allowable stress of the diaphragm material increases. It will be destroyed in a short period of time. Furthermore, if the spring is simply made thicker, the rotating shaft will not slide unless a large amount of force is applied, resulting in hand fatigue. The above-mentioned drawbacks are particularly noticeable when drilling holes in ceilings and the like from below, making conventional vibrating drills extremely difficult to use. (Objective of the Invention) The present invention has been proposed in view of the above points, and aims to increase impact force and improve work efficiency.
The object of the present invention is to provide a vibration drill that reduces worker fatigue and prevents vibration diseases. (Disclosure of the Invention) FIG. 4 shows an embodiment of the present invention, in which two springs 14a and 14b are superimposed and provided between the first diaphragm 12 and the second diaphragm 13. It has the following characteristics. In the figure, two springs 14
One ends of the first spring 14a and 14b are fixed to the inner bottom surface of the vibration housing 3 to which the first diaphragm 12 is fixed, and the other end of the first spring 14a is fixed to the second diaphragm 13.
The other end of the second spring 14b is in a freely released state at a position δ ₂ before the other end of the first spring 14a. Moreover, since the other configurations are the same as those shown in FIG. 1, the same parts are given the same reference numerals and the explanation thereof will be omitted. In operation, after rotational power is applied to the rotating shaft 4, when the drill bit 6 is applied to the material and the drill body 1 is pressed, the rotating shaft 4 slides toward the main body against the repulsive force of the spring. Here, since only the first spring 14a with a small spring constant is acting within the distance δ ₂ until the first and second diaphragms 12 and 13 start contact, the force required for pressing is relatively small. It's small. Then, when further pressing is performed, the first and second
The diaphragms 12 and 13 of the diaphragms 12 and 13 are in complete contact with each other, and vibrations are generated by the collision and running of the uneven ridges provided on the diaphragm surfaces. However, at this time 2
The springs 14a and 14b act together, and the springs 14a and 14b act together.
The energy stored in the spring by one vibration is E ₂ = 1/2 ( _{K 1 + K 2} ) δ ₁ ² ......(2) Since the force of the second spring 14b, which is thicker and has a larger spring constant than the first spring 14a, is applied, the impact force becomes significantly larger. Generally, the pressing force felt by a person's hand is averaged, so
If vibration is started and maintained with a small pressing force, fatigue will be small even if the vibration energy is large. The results of experiments conducted by the inventor are shown below, and it is clear that the impact force is significantly increased compared to conventional vibrating drills.

[Table] (Effects of the invention) As described above, in the vibration drill of the present invention,
A rotating shaft with a drill bit attached to its tip and slidably attached in the axial direction, and a first diaphragm arranged concentrically with the rotating shaft, fixed to the drill body, and provided with continuous irregularities in the circumferential direction. and a second diaphragm that is fixed to the rotating shaft, is arranged opposite to the first diaphragm, and is provided with continuous irregularities in the circumferential direction corresponding to the first diaphragm; Two springs are inserted between the mounting parts of the first and second diaphragms and overlap each other, so that the spring constant during vibration is larger than the spring constant acting on pressing until the vibration starts. With this structure, it is possible to provide a vibration drill that has a large impact force and is not tiring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional vibrating drill, FIGS. 2 and 3 are diagrams for explaining the operation, FIG. 4 is a diagram for explaining the construction of an embodiment of the present invention, and FIG. 5 is a diagram for explaining the operation. 1... Drill body, 4... Rotating shaft, 6... Drill bit, 12, 13... Vibration plate, 14a, 14
b...Spring.

Claims (1)

[Scope of Claims] 1. A rotary shaft with a drill bit attached to its tip and slidably attached in the axial direction; The first surface is provided with unevenness.
a diaphragm fixed to the rotating shaft and arranged opposite to the first diaphragm, and
a second diaphragm having continuous irregularities in the circumferential direction corresponding to the diaphragm; and two springs inserted between the mounting portions of the first and second diaphragms and overlapping with each other. A vibrating drill characterized by comprising: 2. The vibration drill according to claim 1, wherein one of the two springs is shortened in the axial direction to provide a step.