JPS60201809A - Vibrating twist drill - Google Patents

Abstract

PURPOSE:To obtain a large percussion force efficiently and prevent the transmission of vibration onto hands by a small-sized apparatus by transmitting the reciprocative movement of a driving element to a hammer through a mechanical spring. CONSTITUTION:A twist-drill bit 9 is installed at the front edge of a body housing 1. An eccentric pin 24 projecting from the upper edge of a connecting shaft 23 is engaged with the elliptical hole 27 at the rear edge of a rod ring 26 extending from the rear edge of a driving element 4 through a bearing. The driving element 4 is moved in reciprocation in the axial direction by the revolution of a motor 2, and since an intermediate hammer 18 and the twist-drill bit 9 positioned before the hammer 18 are accommodated into an output shaft 4, a hammer 6 which receives the reciprocative movement of the driving element 4 through a coil spring 5 hits the rear edge of the intermediate hammer 18 and transmits the percussion force onto the bit 9. Thus, a large percussion force can be obtained efficiently by a small-sized apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a vibratory drill that rotates a drill bit and simultaneously drives it in the axial direction to provide a striking action.

[Background Art] This vibratory drill includes a piston hammer set shown in Japanese Patent Publication No. 53-46761, and
There is a type of one-tip and one-piece type shown in Japanese Patent No. 53383. In the former case, as shown in FIG. 15, the rotation of the motor 2 is converted into a reciprocating motion of a piston 4' in a sill-8 by an eccentric camshaft 24 and a connecting rod 39, and the movement of the piston 4' is converted into a reciprocating motion of a piston 4' in an air chamber 50. The rotational motion of the motor 2 is transmitted to the hitting hammer 6 of the output shaft 7 through the air spring, and the rotational motion of the motor 2 is transmitted to the output shaft 7 through the gear and the shilling 8. Since this device uses an air spring, it has the characteristic that vibrations are not easily transmitted to the operator. I can't tell 〇. Therefore, the seals 83 of the piston 4' and the free hammer 6 are extremely important. During operation, especially just before the 7-lead hammer 6 hits the output shaft 7, the pressure in the air chamber 50 is 2.
000 Kg/cI112, the contact pressure between these seals 81 and the inner surface of Schilling-8 must also be kept quite high. Therefore, in order to smoothly drive the piston 4' and the free hammer 6, a large amount of power is required, and it is necessary to use a large-sized, high-output motor 2, usually 400 W or more. Furthermore, in order to improve the reliability and life of the sliding parts, oil lubrication is required, which makes the sealing mechanism complicated, and because of the motor 2, it tends to be large and heavy, making it difficult to use.

As shown in FIG. 16, the ratchet type has a pair of ratchet plates 85 and 86 facing each other, and one ratchet plate 85 fixed to the output shaft 7 is connected to the motor 2 via a gear, and the other ratchet plate 85 is connected to the motor 2 through a gear. The ratchet plate 86 is fixed to the main body housing 1 in a non-rotatable manner, and the pressure when pressing the drill bit attached to the output shaft 7 against the material and the engagement of both ratchet plates 85 and 86 are used. This structure provides slight axial vibration to the rotationally driven output shaft. However, this method also has the following problems. In other words, since it uses micro-vibration rather than impact force, its drilling capacity is 1/3 to 1/4 smaller than that of the above-mentioned piston hammer set. If there is, it is possible to drill holes, but in the case of concrete containing aggregate, the capacity is insufficient and the time required to drill holes becomes extremely long. Also, if the motor 2 has a capacity of about IKW, it will be possible to make a hole even if it hits the aggregate, but the main body weight will be 5 to 6K.
g, making it extremely difficult to use.

Furthermore, Komei sometimes felt that the reaction force from the slight vibrations from the drill bit was transmitted to his hands through the fixed ratchet plate 86, making his hands numb and unable to withstand long hours of work, and even pushing the main body with his hands. Only when you press the drill bit against the material do you get micro-vibrations, and since these micro-vibrations are proportional to the pressing force, the reaction force transmitted to your hand also increases in proportion to this, and it also makes it difficult to drill holes into the ceiling. It is extremely difficult to use in places like Akari where the footing is unstable, and it is not practical.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to provide a small and efficient impact force that can be applied efficiently, while also making it difficult for vibrations to be transmitted to the hand. To provide a vibration drill that is less tiring.

[Disclosure 1 of the Invention The present invention provides an output section rotationally driven by a motor,
It is equipped with a hammer that strikes the output section, a driver that is reciprocated by the motor, and a mechanical spring that connects the driver and the hammer and urges the hammer toward the output section. It has the following characteristics: it uses the energy stored in the mechanical spring to obtain a highly efficient impact force, and also uses the mechanical spring to absorb vibrations.

The present invention will be described in detail below based on the illustrated embodiment.The main body housing 1 has a drill bit 9 attached to its front end, and a handle 11 at its rear end. is a storage chamber for a storage battery 13, and an auxiliary handle 12 is provided at the lower part of the front end. 14 is a switch, and 1.5 is a switch handle, which can be operated by the hand holding the handle 11.

The motor 2 is housed in the lower center of the main body housing 1, fixed to the frame 3 with its axis oriented vertically, and has a pinion 21 and a bevel gear 31 on its output shaft 20.
is attached. The pinion 21 meshes with a gear 22 at one end of a rotatably supported connecting shaft 23, and the bevel gear 31 is connected to an intermediate shaft 33 whose axial direction is front and rear.
It meshes with a bevel gear 32 provided at the rear end. A cylindrical cylinder 8 fixed to the frame 3 and a cylindrical output shaft 7 rotatably supported in front of the cylinder 8 are housed in the front part of the main body housing 1. A drive element 4, a hammer 6, and a coil spring 5 connecting the two are housed in a parallel cylinder 8. The drive element 4 located at the rear of the cylinder 8 is attached to the front end of the drive shaft 25, which passes through an end plate 82 at the rear end of the cylinder 8 and is slidably supported in the axial direction by a bearing 29. The fill spring 5 is provided so as to be rotatable around an axis, and the rear end of the fill spring 5 is screwed into a thread groove 40 provided on the outer peripheral surface of the fill spring 5 as shown in FIG. Further, a hammer 6 having a threaded groove 60 into which the front end of the coil spring 5 is screwed is arranged so as to be in sliding contact with the inner surface of the sill-8. A rod ring 26 extends rearward from the rear end of the driver 4, and an eccentric pin 24 protruding from the upper end of the connecting shaft 23 is attached to a horizontally long hole 27 at the rear end of the rod ring 26. are engaged through. In response to the rotation of the motor 2, the driver 4 reciprocates in the axial direction. And the output shaft 7
Since the intermediate hammer 18 and the drill bit 9 located in front of the intermediate hammer 18 are housed inside, the hammer 6, which receives the reciprocating motion of the driver 4 through the coil spring 5, hits the rear end of the intermediate hammer 18. , which transmits impact force to the drill bit 9.

On the other hand, the intermediate shaft 33 to which the rotation of the motor 2 is transmitted through the bevel gears 31 and 32 has a pinion 34 provided at its front end meshing with a gear 35 provided on the output shaft 7 to drive the output shaft 7 in rotation. Being able to do so. The drill bit 9 is attached to the output shaft 7 by engaging a ball 19 protruding from the inner surface of the output shaft 7 with an axially long groove 90 provided at the base end of the drill bit 9. The drill bit 9 rotates together with the output shaft 7.

As is clear from the above, in this vibratory drill, when the motor 2 is rotated, the drill bit 9 receives rotational force from the intermediate shaft 33 and rotates, and the reciprocating motion of the driver 4 is controlled by the coil spring 5. It receives impact force via the hammer 6 and the intermediate hammer 18 and is driven in the axial direction within the engagement range between the ball 19 and the long groove 90.

FIG. 5 shows the point in time when the hammer 6 hits the intermediate hammer 18. The operations of the driver element 4, fill spring 5, and hammer 6 here will be explained in more detail based on FIG. 6. FIG. A tensile force is acting on the Even if the drive element 4 is further retreated from this state as shown in FIG. 4(b), the coil spring 5 is extended because the hammer 6 remains due to its inertia. When the driver 4 reaches the rear end of its reciprocating stroke, the hammer 6 is pulled and begins to move backward as shown in FIG. As shown in FIG. 2, since the moving directions of the driver 4 and the hammer 6 are opposite, the fill spring 5 is compressed and energy is stored. When the driver 4 moves further forward, the hammer 6 moves forward with the energy stored in the coil spring 5 being applied to the movement of the driver 4 received via the coil spring 5, and drills the front end. Bit 9
It collides with the rear end surface of the intermediate hammer 18 which is in contact with the hammer. The movement of the driver 4 and the hammer 6 is shown in FIG. The horizontal axis is time and the vertical axis is displacement. The controller 6 moves in a substantially triangular waveform with a slightly delayed phase relative to the movement of the driver 4 shown by the sine curve. In addition, the forward motion for striking the intermediate hammer 18 of the hammer 6 and the backward motion are compared; when moving backward, the coil spring 5 is compressed, so it is slow, and when moving forward, the force is stored in the fill spring 5. It is faster due to the addition of energy, and provides a powerful striking force. In the figure, T indicates a hitting section.

Also, the impact force here is the fill spring 5 and the hammer 6.
By utilizing the resonance of the system formed by this, it becomes even larger. To explain this point, let us assume that the spring constant of the fill spring 5 is , and the mass of the hammer 6 is M.
The natural frequency f, (c/s) of the above system is fo = (1/2
1r)(k/M)"". Further, the frequency of the driver 4 reciprocally driven by the motor 2 is r, and the amplitude of the hammer 6 is X. , when the amplitude of the driver 4 is X, the value of X/X becomes maximum when the value of f/f reaches 1, which is the resonance point, as shown by the solid line in Fig. 8. By utilizing this resonance, that is, by setting f/f = 1, the impact force can be maximized. However, in this vibrating drill, its power source is the storage battery 13.
As shown in FIG. 11, the power supply voltage decreases as the power supply voltage is used, and as a result, as shown in FIG. The mass M of the hammer 6 in the system of the spring 5 becomes apparently smaller due to the collision, and the natural frequency actually becomes smaller than the above-mentioned theoretical value, as shown by the broken line in FIG.

Considering these points, it is preferable to set f/fo to 1 when the storage battery 13 is fully charged.

In this case, when the storage battery 13 is fully charged, actually f/fo>1, and as the voltage of the storage battery 13 decreases and the power of the motor 2 decreases, that is, the frequency f of the driver 4 decreases. Accordingly, the actual value of f/f approaches 1, which is the resonance point. That is, when the storage battery 13 is fully charged and the power of the motor 2 is at its maximum, the amplitude of the hammer 6 is kept slightly smaller by shifting it slightly from the resonance point, and as the voltage of the storage battery 13 decreases and the power of the motor 2 decreases. The amplitude of the hammer 6 is thick.As a result, regardless of the voltage drop in the storage battery 13, the impact force is always approximately the same value, making it lighter. The rotation of the bit 9 is of course involved in crushing, but it is also used to discharge chips of concrete, etc. crushed by the impact out of the hole.

Incidentally, the sill 8 that guides the reciprocating motion of the hammer 6 has an air hole 8 long in the axial direction on its lower end surface.
0 is set. This air hole 80 is provided to prevent the air inside the cylinder 8 from becoming a resistance to the operation of the hammer 6. However, this air hole 80
The position where it forms is further rearward from the cushion plate 83 on the back surface of the end plate 81 at the front end of the Schilling-8 and from the position indicated by Q in the figure. This is because the air at the front end of the Schilling-8, together with the cushion plate 83, plays a role in mitigating the impact during blank firing. When the hammer 6 is working, the hammer 6 always collides with the rear end of the intermediate hammer 18 and hits the end plate 81 after its kinetic energy is reduced. This will not cause damage to the end plate 81, but when the hammer 6 hits the end plate 81 directly, the kinetic energy of the hammer 6 is large, so there is a risk that the end plate 81 will be damaged. be. Of course, the cushion plate 83 is provided to alleviate this impact, but this alone is not sufficient. To this end, the hammer 6 compresses the air in the space between the hammer 6 and the end plate 81 in the cylinder 8 from a position just before it advances and collides with the intermediate hammer 18. This allows the air to act as a buffer spring.

In addition, the connection between the coil spring 5 and the driver 4 and the coil spring 5
The drive element 4 and the hammer 6 are connected by a threaded connection utilizing the shape of the coil spring 5, respectively, as described above.
The reason why the drive shaft 25 is rotatable around the drive shaft 25 is as follows. That is, the screw connection facilitates the connection work between these members, and also prevents the rotation of the output shaft 7 from being transmitted to the hammer 6 through the intermediate hammer 18, thereby preventing twisting of the coil spring 5. Now, when the driver 4 is fixed to the drive shaft 25,
Excessive torsional force acts on the coil spring 5 and the fill spring 5
Otherwise, the coil spring 5 may expand in diameter due to torsional force, causing the coil spring 5 to become disconnected from the hammer 6 and the driver 4, or come into contact with the inner surface of the cylinder 8, increasing the sliding load. This is what is being prevented.

Furthermore, in the illustrated example in which the handle 11 and the switch handle 15 are arranged in a straight line on the axis of the drill bit 9, the impact force between the user's load point on the vibration drill and the impact force of the drill bit 9 when drilling is Since the points of force are aligned in a straight line, the force required to hold the main body housing 1 is small, making it extremely easy to use. In addition, when using the back-type storage battery 13 as a power source, it is preferable that the contact surface between the contact spring 65 on the main body housing 1 side and the connection terminal 66 on the storage battery 13 side coincide with the vibration direction as shown in the illustrated example. If these lines intersect, when vibration is applied to the storage battery 13, the contact pressure between the connection terminal 66 and the contact spring 65 will be greatly affected, making it impossible to drive the motor 2 stably. Since they are parallel, the motor 2 can be driven stably even if the storage battery 13 vibrates.

FIG. 11 shows another embodiment. The motor 2 is housed in the upper part of the rear end of the housing 1, which is located on the axis of the drill bit 9, and a handle 11 is arranged in the lower part of the rear end. By positioning it on the axis of the drill bit 9, the center of gravity is brought close to the axis, and by positioning the storage battery 13 on the side of the drill bit 9 with a space between the handle 11 and the handle 11, an extraordinary rotational moment can be generated during drilling. This is to prevent this from occurring. To transmit the rotational force to the drill bit 9, an intermediate shaft 33 is provided with a gear 22 that meshes with a pinion 21 fixed to the output shaft 20 of the motor 2, and a chuck is provided at the tip of the pinion 34 at the tip of the intermediate shaft 33. The reciprocating motion of the driver 4 for driving the drill bit 9 in the axial direction is caused by the output shaft 20 of the motor 2. 1/Gold tooth 111t211: This is done by meshing the bevel gear 32 provided on the connecting shaft 23 on the right side of Danpachi Pn 24 and directly striking the output shaft 7 with the hammer 6. Furthermore, the cylinder 8 for guiding the hammer 6 here is made up of a plurality of rods 81, except for its front and rear ends, as shown in FIG. 12, and has improved heat dissipation characteristics. .

FIG. 13 shows still another embodiment. In this case, the coil spring 5 in the embodiment shown in FIGS. 11 and 12 is a conical spring having a nonlinear spring constant. As mentioned above, the impact force applied to the drill bit 9 is through the fill spring 5, and the reaction force is also through the fill spring 5, so vibration is reduced compared to the conventional ratchet type. However, if resonance is used to increase the impact force as described above, the vibration damping effect of the fill spring 5 cannot be expected to be that great.

However, this conflicting point can be resolved by using a coil spring 5 having a non-linear spring constant, such as a conical spring as shown in the illustrated example, or a coil spring having a non-uniform wire diameter. In other words, f/
It is said that it is preferable to set f to >2'', but this condition will be violated if resonance is used to increase the striking force.However, as shown in Fig. 14,
When the displacement is δ and the load is P, instead of the linear spring constant k2δ/P, k=δT1/P (n>1
) Fill spring 5 with a nonlinear spring constant given by
When using , the spring stored energy, which is represented by (1/2) kδ2 and is applied to the hammer 6, is extremely large because it is when the coil spring 5 is most compressed and the spring constant k is maximum. It becomes a big hit, and the hitting power increases. When the hammer 6 collides with the intermediate hammer 18, the coil spring 5 is stretched, that is, the spring constant is small and the natural frequency f is reached. The value of r/r becomes smaller, and the value of r/r becomes a value that is advantageous for the vibration damping effect. It will be successful if it satisfies both extraordinary striking power and anti-vibration effect.

[Effect of the invention 1 As described above, in the present invention, the reciprocating motion of the drive element is transmitted to the striking hammer via a mechanical spring, and for this reason, a large striking force can be obtained, and the sealing can be improved. It is possible to make a compact and highly efficient device because there is no need to adjust the amount of vibration, and the sliding resistance can be reduced, and the recoil of vibration can be absorbed by the mechanical spring. It is possible to make the device less tiring and easy to use.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of one embodiment of the present invention, Fig. 2 is a broken perspective view of the same, Fig. 3 is a sectional view taken along line A-A in Fig. 1, and Fig. 4 is a rond ring and eccentricity of the same. A plan view of the pin, FIG. 5 is a vertical sectional view of the same as above, FIGS. Figure 8 is a characteristic diagram of the vibration ratio and amplitude ratio as above,
Fig. 9 is a voltage characteristic diagram of the storage battery, Fig. 10 is a characteristic diagram of the motor, Fig. 11 is a vertical sectional view of another embodiment, and Fig. 12 is a
13 is a longitudinal sectional view of another embodiment, FIG. 14 is a characteristic diagram of the spring constant of the same as above, and FIG.
16 and 16 are respectively cutaway front views of the conventional example, and 1
2 is a main body housing, 2 is a motor, 4 is a driver, 5 is a coil spring as a mechanical spring, 6 is a hammer, 7 is an output shaft, and 9 is a drill bit. Agent Patent Attorney Ishi 1) Chief 7 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 [l■q〒

Claims (10)

[Claims] (1) An output part rotationally driven by a motor, a hammer that strikes the output part, a driver driven reciprocally by the motor, and the driver and hammer are connected and the hammer is directed toward the output part. A vibratory drill comprising: a mechanical spring that biases the vibration drill. (2) The ratio f/f between the natural frequency f of the spring system, determined by the spring constant of the mechanical spring and the 'RR' of the hammer, and the frequency f of the reciprocating motion of the driver is approximately 1. A vibratory drill according to claim 1. (3) The vibration according to claim 1, wherein the mechanical spring is a coil spring, and both ends of the mechanical spring are threadedly connected to threaded parts provided on the driver and the hammer, respectively. Drill. (4) The vibratory drill according to claim 1, wherein the mechanical spring has a nonlinear spring constant. (5) The vibratory drill according to claim 1, wherein the sill whose inner surface the hammer slides on is provided with an air hole that communicates the inner and outer spaces of the sill. (6) The vibratory drill according to claim 1, wherein the motor power source is a storage battery housed in the drill body. (7) The motor is arranged at a position that intersects with the axial direction of the output section, and the lower part of the handle provided parallel to the motor is connected to a contact spring provided on the drill body in a direction perpendicular to the axial direction of the output section. 2. The vibratory drill according to claim 1, wherein a battery is housed therein, the battery having a connecting terminal at which contact pressure is generated. (8) The motor is disposed on the axis of the output section, and the battery is disposed in the handle intersecting the axial direction of the output section with a space therebetween. Vibration drill. (9) The natural frequency f of the spring system is determined by the spring constant of the mechanical spring and the mass of the hammer. and the frequency f of the reciprocating motion of the driver driven by the motor to which the storage battery voltage is applied when fully charged, f/fo, is set to a value larger than 1 and close to 1. A vibratory drill according to claim 6. (10) The vibratory drill according to claim 1, wherein the battery is disposed closer to the output section than the handle.