JP4180857B2 - Impact tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a striking tool capable of transmitting a striking action to a bit attached to the tip.
[0002]
[Prior art]
The striking tool pivotally supports a tool holder in which a bit can be mounted in a housing, and a reciprocating piston driven by a motor is accommodated in the tool holder, and a striking element is disposed in front of the piston via an air chamber. The striking element can be moved forward and backward with a predetermined stroke in conjunction with the piston. Similarly, in the tool holder, an intermediate element is housed in front of the striker so as to be movable back and forth, and retreat is restricted by a restricting member such as a washer. The striking operation can be transmitted to the bit by striking the stopped meson.
In addition, an O-ring is provided between the intermediate element and the striking element in the tool holder so that the striking element that has advanced beyond a predetermined stroke can be gripped. In a state in which the striker is not pressed against the ground or the like, the striker that has advanced with the first strike on the intermediate element is held by the O-ring, and the advancement / retraction (empty strike) of the striker thereafter can be prevented.
[0003]
[Problems to be solved by the invention]
In the impact tool described above, since the O-ring is directly assembled to the inner surface of the tool holder, the inner shape of the tool holder is complicated, the processing cost is increased, and the assembly is troublesome.
On the other hand, when the striker strikes the intermediate element, the impact due to the strike is transmitted to the tool holder and the housing via the restricting member, which makes the operator's hand uncomfortable.
[0004]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a striking tool that does not increase the processing cost even when an O-ring is used as a gripping member of the striking element and has good assemblability. .
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is configured such that the O-ring is held in an O-ring case fixed in the tool holder, and can be moved back and forth in the tool holder in front of the O-ring case. A flat washer that restricts forward movement is provided at the contact position with the step formed on the inner periphery of the tool holder, and the second O-ring is in contact with the O-ring case and the flat washer. By interposing the intermediate element, the intermediate element moves backward and comes into contact with the flat washer, whereby the backward movement of the intermediate element can be regulated .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial longitudinal sectional view of an electric hammer as a striking tool. A motor shaft 4 of a motor (not shown) arranged in parallel to the main body axial direction behind the electric hammer 1 is arranged in the main body axial direction. Is engaged with a spiral bevel gear 6 that is integral with a crankshaft 5 that is supported orthogonally to the crankshaft, and the crankshaft 5 is rotated. The crankshaft 5 is provided with an eccentric pin 7 projecting from a piston 11 and a rod 12 which are loosely inserted into a cylinder portion 9 behind the tool holder 8 which is coaxially supported by the main housing 3. These crank mechanisms convert the rotation of the motor shaft 4 into the reciprocating motion of the piston 11. The main housing 3 extends rearward in addition to the shaft support of the tool holder 8, and supports the ball bearing 13 that supports the crankshaft 5 and the ball bearing 14 that supports the motor shaft 4. This is an integrally molded product that reduces the vibration inside the electric hammer.
[0007]
Further, the cylinder portion 9 of the tool holder 8 is pivotally supported by the main housing 3 by rings 15 and 16 arranged at the front and rear, and an impactor 18 is moved forward and backward through an air chamber 17 in front of the piston 11. The striking element 18 is moved forward and backward in conjunction with the movement of the piston 11 by the action of the air spring. Further, the striking element 18 that moves forward and backward strikes the intermediate element 19 that is housed so as to be movable forward and backward, and strikes the rear end of the bit attached to the tool holder 8 so that the striking operation can be transmitted to the bit. It has become.
[0008]
In the tool holder 8, a flat washer 20, an O-ring 21 as a second O-ring, and an O-ring case 22 are housed between the intermediate element 19 and the striker 18 from the front. Each of these parts is axially formed by a step formed on the inner periphery of the tool holder 8 in front of the flat washer 20 and a ring locked on the inner periphery of the tool holder 8 behind the O-ring case 22. The movement is restricted, and the O-ring 21 is sandwiched between the flat washer 20 and the O-ring case 22. Among these, the flat washer 20 restricts the backward movement of the intermediate piece 19 by the contact of the intermediate piece 19 pushed backward by the bit 40 as shown in FIG. Therefore, the O-ring 21 that abuts behind the flat washer 20 functions as a buffer member that receives the meson 19 and the flat washer 20.
[0009]
On the other hand, an O-ring 23 as a gripping member is held on the inner peripheral side of the O-ring case 22. As shown in FIG. 1, when the motor is driven in a state where the bit 40 is not attached or the attached bit 40 is not pressed against the ground as shown in FIG. The tip of the striker 18 that has advanced beyond this stroke is gripped, and the subsequent linkage with the piston 11 is prevented (empty strike prevention function).
[0010]
Further, a small-diameter chuck portion 10 is continuously provided in front of the tool holder 8, and a chuck cover 24 is externally mounted on the chuck portion 10 so as to be movable back and forth. Similarly, inside the chuck cover 24, a chuck ring 25 is externally mounted on the chuck portion 10 so as to be movable back and forth, and the chuck cover 24 and the chuck ring 25 are provided by a compression spring 27 between the front end and a spring guide 26. Are biased in directions opposite to each other. However, a stopper pin 28 that loosely penetrates the chuck portion 10 is loosely inserted into the chuck ring 25, and the stopper pin 28 is urged toward the axial center by a leaf spring 29 wound around the outer periphery of the chuck ring 25. Thus, since the head of the stopper pin 28 is engaged to restrict the movement of the chuck ring 25 in the axial direction, normally, the chuck cover 24 moves forward and reaches the most advanced position where it abuts against the cap 30. is there. Reference numeral 31 denotes a steel ball which is disposed on the outer periphery of the chuck portion 10 and is pressed toward the axial center side by the advancement of the chuck ring 25.
[0011]
On the other hand, between the chuck cover 24 and the cover 2, a change ring 32 that is externally attached to the front portion of the cylinder portion 9 of the tool holder 8 is disposed. The change ring 32 has a two-stage cylindrical shape in which a front end is loosely inserted into the chuck cover 24 and a rear end is externally fitted to the cover 2 and exposed to the outside. A spring guide 33 disposed at the rear end of the chuck ring 25 and It is urged backward by the compression spring 34 between the two. Further, the change ring 32 has a double cylinder shape in which a small diameter cylinder 32a that is externally mounted on the cylinder portion 9 is continuously provided. As shown in FIG. 3, four slides are formed on the outer periphery of the cylinder portion 9 at equal intervals. By fitting the grooves 35, 35,... And the slide protrusions 36, 36,... Formed on the inner periphery of the small diameter cylinder 32a, the change ring 32 is integrated with the tool holder 8 and can only be slid. Furthermore, the change ring 32 normally abuts against the front end of the main housing 3 by the urging force of the compression spring 34, but as shown in FIG. 4, the front end of the main housing 3 and the rear surface of the change ring 32 are respectively engaged. Engagement teeth 37, 37,... And 38, 38,... Serving as joints project from each other so as to mesh with each other, and the rotation of the change ring 32 can be restricted.
[0012]
In the electric hammer 1 configured as described above, when the bit 40 is mounted, the rear end of the bit 40 is inserted into the chuck portion 10 of the tool holder 8 from the normal state of FIG. Since the stopper pin 28 is pushed up by abutting against the tip of the pin 28, the locking of the head of the stopper pin 28 and the chuck ring 25 is released, and the chuck ring 25 is biased by the compression spring 34 (here, the rear side). The compression spring 34 is moved forward (because a spring having a larger urging force than the compression spring 27 on the front side is used), and the steel ball 31 is pressed toward the axial center side. Therefore, as shown in FIG. 2, the steel ball 31 protruding toward the axial center side engages with the lock groove 41 of the bit 40, and the bit 40 is attached to the tool holder 8.
If it is desired to change the angle of the bit 40, when the change ring 32 is grasped and slid forward, the engagement teeth 38 on the rear surface and the engagement teeth 37 on the main housing 3 side are engaged as shown in FIG. Therefore, the tool holder 8 is rotated by the change ring 32 as it is, and the bit 40 can be changed to an arbitrary angle. In addition, since the forward slide of the change ring 32 is regulated by the contact with the spring guide 33, the fitting between the slide groove 35 and the slide protrusion 36 is always maintained regardless of the forward slide position. When the change ring 32 is moved backward after the angle change, the engagement teeth 38 on the rear surface and the engagement teeth 37 on the main housing 3 side are engaged again, and the rotation of the change ring 32 and the tool holder 8 is locked at this position. Will be.
[0013]
Thus, according to the electric hammer 1 of the said form, the O-ring 23 which hold | grips the striker 18 is hold | maintained to O-ring case 22 fixed in the tool holder 8, and the inner surface shape of the tool holder 8 is carried out. Becomes easier. Therefore, even if the O-ring 23 is used as a gripping member, the processing cost can be suppressed and the assemblability can be improved.
Further, by holding the O-ring 21 between the flat washer 20 and the O-ring case 22, the impact generated during the normal striking operation is effectively mitigated, and the impact transmitted to the tool holder 8, the main housing 3, and the cover 2 is reduced. Get smaller. Therefore, the operator's feeling of use becomes good.
[0014]
【The invention's effect】
According to the invention described in claim 1, by holding the O-ring in the O-ring case fixed in the tool holder, the inner shape of the tool holder can be simplified, and the O-ring can be used as a gripping member. Processing costs are reduced and assemblability is improved.
In particular, by holding the second O-ring between the flat washer and the O-ring case, the impact generated during the normal striking operation is effectively mitigated, and the impact transmitted to the tool holder, housing, etc. is reduced. The feeling of use becomes good.
[Brief description of the drawings]
FIG. 1 is a partial longitudinal sectional view of an electric hammer (in a state where no bit is attached).
FIG. 2 is a partial vertical sectional view of the electric hammer (with a bit attached).
FIG. 3 is an enlarged end view taken along line AA.
FIG. 4 is an enlarged end view taken along line BB.
FIG. 5 is an explanatory view showing a state in which the change ring is slid forward.
[Explanation of symbols]
1 .... Electric hammer, 2 .... Cover, 3 .... Main housing, 8 .... Tool holder, 9 .... Cylinder part, 10 .... Chuck part, 11 .... Piston, 17 .... Air chamber, 18 .... Blow Child, 19 ... meson, 20 ... flat washer, 21, 23 ... O-ring, 22 ... O-ring case, 24 ... chuck cover, 32 ... change ring, 34 ... compression spring, 35 ... slide Groove, 36 ... slide protrusion, 37, 38 ... engaging tooth, 40 ... bit.

Claims (1)

A tool holder that is pivotally supported in the housing and can be fitted with a bit accommodates a piston that reciprocates by motor drive, accommodates a striker through an air chamber in front of the piston, and places the striker on the piston. The reciprocating motion is possible in a predetermined stroke in conjunction with the striking element, and an intermediate element that receives the rear end of the bit is accommodated in front and rear of the striking element so as to be movable back and forth , and between the striking element and the intermediate element, A striking tool provided with an O-ring capable of gripping the striking element when the striking element advances beyond the predetermined stroke,
While holding the O-ring in an O-ring case fixed in the tool holder, it is possible to move back and forth in the tool holder in front of the O-ring case and to a step formed on the inner periphery of the tool holder. A flat washer that restricts forward movement at the abutting position is provided, and a second O-ring is interposed between the O-ring case and the flat washer in the abutting state, so that the intermediate element moves backward to A striking tool characterized by being able to regulate the backward movement of the meson by contacting a flat washer .

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