JPH0630846B2 - Impact tool - Google Patents

Description

TECHNICAL FIELD The present invention relates to an impact tool such as an electric hammer drill.

[Background technology]

Conventionally, in an impact tool such as an electric hammer drill, the rotational motion of a motor is transmitted through a gear group, and reciprocating motion is generated by an eccentric shaft to transmit the rotational motion and the reciprocating motion to a bit such as concrete. Perform drilling work.

Here, there is a so-called blank hitting state in which the bit is hit when it is not in contact with the workpiece (a state in which the bit is subject to hitting force but is not actually crushed), or the bit is inserted. If not, the striker and the hammer hit the main body holding member, so it is necessary to absorb the impact energy of these strikers.

Therefore, the one shown in FIG. 4 (Japanese Patent Publication No. 50-33965)
Alternatively, the one shown in FIG. 5 (Japanese Utility Model Publication No. 54-25107) has been proposed.

The example of FIG. 4 is provided with a shock absorber by the air chamber 60. 61 is a cylinder, 62 is a piston driven by a motor 64 via a crank 63, 65 is a bit, 66
Is a blower. With this configuration, the air chamber 67 formed at the front end of the striker 66 is repeatedly compressed and expanded by the piston 62 that reciprocates when the switch is on, and due to the atmospheric pressure and the pressure difference between the air chambers 67, 67. Striker 6
6 reciprocates and strikes bit 65. However, even at the time of idling as shown in the figure, the air chamber 67 is compressed and expanded, so that not only the piston 66 but also the striker 66 does not work on the bit 65, but reciprocating motion occurs. is doing. Further, since the air chamber 60 formed by the cylinder 62 and the striker 66 for cushioning the idle shot is compressed, the work amount does not change much even during the idle shot, and the electric power is consumed. Is especially disadvantageous. Also,
The sliding noise of the impact force is large and the vibration of the main body is large.
Further, since the air in the air chambers 60 and 67 is repeatedly compressed and expanded, the temperature of the mechanism portion rises, and in the lubrication of grease or the like, the sealing property of the grease and the temperature resistance quality also become a problem.

In the example of FIG. 5, a holding ring 72 that holds the striker 70 at the tip of a cylinder 71 is provided. In this example,
The reciprocating motion of the striker 70 is similar to that of the piston 73.
The air is compressed and expanded in the air chamber 74 formed by the striking element 70. Then, when hitting the ball 70,
The striker 70 in the position held by the holding ring 72
The compression / expansion of the air chamber 74 formed by the piston 73 and
Even with this type of blank driving prevention structure, a large amount of work (electric power) is required to drive the piston, and the heat generated by the mechanism is also high.

[Object of the Invention]

It is an object of the present invention to provide an impact tool which has less useless operation and resistance during use or idle driving, consumes less power, and produces less noise and vibration.

[Disclosure of Invention]

The impact tool of the present invention comprises a cylinder accommodating a piston, a hammer movably provided in the cylinder in the axial direction, and a cylindrical spindle provided at the front end of the cylinder struck by the hammer. The striker that moves in the direction and transmits the striking force to the bit, and is provided at the front end of the cylinder and the front end of the hammer, respectively, and is joined by the forward movement of the hammer and can be separated by the impact of the striker in the backward direction. Connection part and connected part, a first air hole provided at a position of the front end of the cylinder closed by the hammer in a state where the connection part is connected to the connection part, and a connection state of the connection part A second air hole formed in the cylinder slightly rearward of the hammer located in the cylinder, and the coupling portion is coupled to the coupled portion. In which the front end of the Sunda and to form an air chamber which is compressed by the hammer between the front end of the hammer.

According to the structure of the present invention, since the bit is pressed against the object to be drilled and the striker projects into the cylinder during punching, the hammer strikes the striker by driving the piston, and the bit is impacted. At this time, since the cylinder inner space in front of the hammer is opened by the first air hole, the hammer does not attenuate the striking force, so that the hammer strikes the striker smoothly and efficiently imparts the striking force to the bit. Therefore, power consumption is low.

Further, at the time of idle driving, the first idle driving causes the hammer to join the joined portion and the joined portion at the front end of the cylinder, and the striker is pulled into the spindle. At this time, the hammer is located in front of the second air hole, and the space in the cylinder between the piston and the hammer is open to the atmosphere.
Therefore, the piston simply reciprocates without compressing the air, and therefore consumes less power, reduces sliding noise in the cylinder, and reduces vibration of the housing.

Furthermore, when the hammer that is blown out by idle driving reaches the front end position of the cylinder, an air chamber is created between the hammer and the front end of the cylinder, and the air chamber is compressed by the hammer, so the large impact of the hammer is buffered and While being transmitted, without excessively coupling the joined portion and the joined portion,
Can be surely combined.

Embodiment An embodiment of the present invention is shown in FIGS. In the figure, reference numeral 1 denotes a housing, a handle 2 is integrally formed on a rear portion, and an auxiliary handle 3 is detachably attached to a front portion. A motor 4 is housed in the housing 1 at the rear end. Reference numeral 5 is a storage battery serving as its power source, 6 is a battery cover, 7 is a lock cover, 8 is a switch, and 8'is a switch operator. The rotation of the motor 4 is transmitted from the pinion 9 attached to its output shaft to the gear 11 at one end of the intermediate shaft 10. This rotation is transmitted to the cylinder 14 by the pinion 12 and the gear 13 attached to the other end of the intermediate shaft 10 in one path. The cylinder 14 is rotatably supported by a gear box 17 by bearings 15 and 16. A cylindrical spindle 20 is provided on the tip side of the cylinder 14.
Is engaged and the stop key 21 ′ is inserted into the key groove provided in the cylinder 14 and the spindle 20, whereby the rotation of the cylinder 14 is transmitted to the spindle 20,
Passed to bit 21. Bit 21 and spindle 20
Are engaged with the transmission key 22. 26 is a press nut. A chuck sleeve 23 on the spindle 20,
A bit cover 24 and a dustproof ring 25 are provided.

On the other hand, the rotation of the intermediate shaft 10 is transmitted to the movable clutch member 28 by the meshing portion 29 of the involute spline convex portion provided on the outer periphery thereof and the involute spline concave portion 29 provided on the movable clutch member 28. A bevel gear claw 28a is formed at an end of the movable clutch member 28 on the bevel gear 30 side, and a bevel gear 30 is also formed with a clutch claw so as to mesh with the clutch claw 28a. Reference numeral 31 is a coil spring, and 32 is a disc spring. First
As shown in the drawing, when the clutch pawl 28a is engaged, the rotation of the intermediate shaft is transmitted to the eccentric shafts 35 and 36 through the bevel gears 30 and 33, and the piston 38 provided at the tip of the connecting rod 37 is It reciprocates in the cylinder 14.
38 'is a drive pin. Similarly, a hammer 39 that strikes the striker 44 is slidably provided in the cylinder 14. The striker 44 is provided in the spindle 20 so as to be movable in the axial direction. At the front end of the cylinder 14 and the front end of the hammer 39, a pyramidal projection 41 serving as a coupling portion and a pyramidal recess 40 serving as a coupled portion are detachably coupled to each other.
Is provided. Further, the cylinder 14 is provided with a first air hole 18 and a second air hole 19 for preventing idling. The first air hole 18 is provided near the front end of the cylinder 14,
The air hole 19 is located slightly behind the hammer 39 when the hammer 39 is located at the front end of the cylinder 14. The striker 44 has a seal member 45 such as an O-ring fitted in a circumferential groove formed on the outer circumference.

Operation The rotation of the motor 4 is carried out from the pinion 9, the gear 11 to the intermediate shaft 1
0 is transmitted to the cylinder 14 by the pinion 12 and the gear 13. Therefore, the bit 21 rotates together with the cylinder 14. The rotation of the intermediate shaft 10 is
The piston 38, which is transmitted to the eccentric shafts 35 and 36 through the clutch member 28 and the bevel gears 30 and 33 and is provided on the connecting rod 37, reciprocates in the cylinder 14. For this reason,
The compression / expansion of the air in the cylinder 14 is repeated, the hammer 39 strikes the striker 44, and the bit 21 is reciprocated. When the clutch member 28 is disengaged from the bevel gear 30 with a switching lever (not shown), the piston 38 is connected to the motor 4
Is not transmitted, the bit 21 only rotates. Therefore, depending on the material to be perforated, it is possible to select perforation only by rotation or rotational impact.

The impact will be described in more detail. When the bit 21 is attached and the bit 21 is pressed against the object, the striker 44 projects into the cylinder 14, and the striker 44 is struck by the hammer 39 to give a struck force to the bit 21. At this time, the striker 44 and the hammer 39 transmit the striking force without damping because there is an air inlet / outlet of the first air hole 18 in the air chamber formed in the cylinder 14. At the time of idle driving, as shown in FIG. 3, the first striker 44 causes the striker 44 to move to the cylinder 14
Move from inside to inside the spindle 20. At this time, the seal member 45 provided at the end of the striker 44 is attached to the spindle 2
Enter the 0 hole. Further, since the hammer 39 also does not serve as a striking resistor, it is blown to the front end of the cylinder 14 and is press-fitted and coupled at the convex portion 41 and the concave portion 40 provided on the cylinder 14 and the hammer 39. At this time, the cylinder 14
In order to close the first air hole 18 provided at the outer periphery of the hammer 39, the space formed between the hammer 39 and the striker 44 in the cylinder 14 together with the seal member 45 of the striker 44 becomes a hermetically sealed state, and therefore the convex portion 41 And the recess 40
The press-fitting connection of can be set to an appropriate holding force. In this way, for the hammer 39 positionally supported in the first blank hit,
The piston 38 constantly reciprocates, but the hammer 39
Is advanced further than the position where it strikes the striker 44 during drilling to open the second air hole 19 of the cylinder 14, so that the pressure in the space inside the cylinder 14 between the piston 38 and the hammer 39 is independent of the reciprocating motion of the piston 38. However, the atmospheric pressure is generally about atmospheric pressure, and the hammer 39 is not pulled back to the piston 38 side against the holding force of the recess 40, and the hammer 39 is stopped. In order to remove the hammer 39 from the tapered surface 40 of the cylinder 14, the bit 21 may be mounted and pressed against the object to be drilled, whereby the hammer 39 is returned to the original position via the striker 44.

Although it operates in this way, since the cylinder inner space in front of the hammer 39 is opened by the first air hole 18 at the time of perforation, the hammer 39 does not attenuate the striking force, and strikes the striker 44 smoothly. Efficiently transmit the striking force to the bit 21. Therefore, it consumes less power.

At the time of idle driving, the hammer 39 is positioned in front of the second air hole 19 and locked to the cylinder 14. Therefore, the piston 38 only reciprocates in the open air chamber and does not compress the air, so that the power consumption is small, the sliding noise in the cylinder 14 is small, and the vibration of the housing 1 is small.

Further, the hammer 39, which has been blown off by blank driving, reaches a certain position, and then the seal member 45 provided on the striker 44.
Since the closed air chamber is created by closing the first air hole 18 of the hammer 39, a large collision of the hammer 39 is buffered and transmitted to the cylinder 14, and the convex portion 41 and the concave portion 40 are also formed.
It can be pressed too much.

〔The invention's effect〕

In the impact tool of the present invention, since the bit is pressed against the object to be drilled during drilling and the striker projects into the cylinder,
The striker is hit by the hammer by driving the piston,
The bit is shocked. At this time, since the cylinder inner space in front of the hammer is opened by the first air hole,
The hammer hits the striker smoothly without damaging the hitting force, and efficiently gives the hitting force to the bit. Therefore, power consumption is low.

Further, at the time of idle driving, the first idle driving causes the hammer to join the joined portion and the joined portion at the front end of the cylinder, and the striker is pulled into the spindle. At this time, the hammer is located in front of the second air hole, and the space in the cylinder between the piston and the hammer is open to the atmosphere.
Therefore, the piston simply reciprocates without compressing the air, and therefore consumes less power, reduces sliding noise in the cylinder, and reduces vibration of the housing.

Furthermore, when the hammer that is blown out by idle driving reaches the front end position of the cylinder, an air chamber is created between the hammer and the front end of the cylinder, and the air chamber is compressed by the hammer, so the large impact of the hammer is buffered and While being transmitted, without excessively coupling the joined portion and the joined portion,
The effect is that they can be surely combined.

[Brief description of drawings]

FIG. 1 is a sectional view showing a hammer striking state at the time of punching according to an embodiment of the present invention, FIG. 2 is a partial sectional view showing a hammer detached state at the time of punching, and FIG. 3 shows an idle striking state. Partial sectional views, FIG. 4 and FIG. 5 are cutaway front views of a conventional example. 1 ... Housing, 4 ... Motor, 10 ... Intermediate shaft, 1
2 ... Pinion, 13 ... Gear, 14 ... Cylinder, 1
7 ... Gear box, 18 ... First air hole, 19 ...
Second air hole, 20 ... Spindle, 21 ... Bit,
28 ... Clutch member, 30, 33 ... Bevel gear, 35,
36 ... eccentric shaft, 37 ... connecting rod, 38 ... piston, 39 ... hammer, 40 ... recess (locking portion), 41 ...
... Convex part (locked part), 44 ... striker, 45 ... seal member

Claims (3)

[Claims] 1. A cylinder accommodating a piston, a hammer movably provided in the cylinder in the axial direction, and a cylindrical spindle provided at the front end of the cylinder struck by the hammer in the axial direction. A striker that moves to transmit a striking force to the bit and a front end portion of the cylinder and a front end portion of the hammer that are respectively coupled to each other by forward movement of the hammer and detachable by impact of the striker in the backward direction. And a coupled portion, a first air hole provided at a position of the front end of the cylinder that is closed by the hammer in a state where the coupling portion is coupled to the coupled portion, and the coupling portion is in the coupled state. A second air hole formed in the cylinder slightly rearward of the hammer, the front portion of the cylinder in a state where the joint portion is joined to the joined portion. Impact tool forming an air chamber which is compressed by the hammer between the front end of the hammer and. 2. A seal member is provided on the outer circumference of the striker to seal a gap between the striker and the inner circumference of the spindle when the striker moves by idle hammering into the spindle. ) Item impact tool. 3. The connected portion of the cylinder and the connecting portion of the hammer are formed by a conical convex portion and a conical concave portion,
The impact tool according to claim (1), which is press-fitted and coupled by the forward movement of the hammer.