JP3993400B2 - Impact tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a striking tool such as an electric hammer equipped with a blanking prevention device that does not cause a striking operation (blank strike) in a so-called no-load state such as when a bit is not mounted or when the bit is separated from the ground or the like.
[0002]
[Prior art]
For example, in an electric hammer, a cylinder is provided in a cylindrical housing connected to a tool holder that can be inserted by inserting a bit into the tip, and a piston that reciprocates by motor drive and an air chamber in front of the piston are provided in the cylinder. And a striker (also called a striker) that moves forward and backward with a predetermined stroke. On the other hand, an intermediate element (also called an impact bolt) with which the rear end of the bit abuts in front of the striker in the housing, and a cylindrical receiver that can pass through the rear part of the intermediate element and are restricted from moving backward at a predetermined position. When the motor is driven in a state where the member is movably moved back and forth and the bit is pushed in, the striker that reciprocates by conduction with the piston strikes the rear part of the intermediate member protruding from the receiving member, and the bit at the tip The blow operation can be transmitted.
[0003]
On the other hand, in such a striking tool, an idling prevention device that prevents a striking operation from occurring in a no-load state (a state where no bit is attached to the tool holder or a state where the bit is not pressed against the ground or the like). Is provided. As this idle driving prevention device, a projecting portion is provided at the front end of the striker, and the intermediate member is separated from the receiving member by the first idle driving by the striker, and at the same time, the projecting portion is held by the receiving member, When the meson that has moved away from the receiving member in the first idle shot bounces back against the tool holder, the receiving member rebounds. A structure or the like is employed in which the amount of movement backward is reduced by the resistance at the time of press-fitting to prevent subsequent hitting by the striker.
[0004]
[Problems to be solved by the invention]
However, when the striker is held by the member as in the former case, the bit hit through the intermediate element in the first idle shot moves forward, collides with the stopper of the tool holder and bounces back to retract the intermediate element. By doing so, the retracted meson may receive the striker from the member and be interlocked with the piston again. Further, in the case where the receiving member is gripped by the receiving member as in the latter case, if the moving amount of the receiving member and the returning intermediate member due to the rebound of the bit in the first idle driving is large as described above, the striking member is hit again. There is a risk of being.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a striking tool that can reliably prevent idling even if a bit rebounds in a no-load state.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a connecting means between the receiving member and the striker, wherein the striker advanced from a predetermined stroke can be elastically connected to the receiving member. The holding member is provided with gripping means capable of elastically holding the rear part of the inserted meson, so that the meson can be released from the receiving member when the meson is first hit by the striker in an unloaded state. The striking element that has been moved forward is connected to the receiving member via the connecting means, and the rear part of the intermediate element that bounces back after detachment from the receiving member is connected to the receiving member via the gripping means. is there.
According to a second aspect of the present invention, in addition to the object of the first aspect, in order to form the connecting means and the gripping means in a simple and compact manner, the connecting means is provided with a convex portion provided on the rear surface of the receiving member, and an impact. A recess provided on the front surface of the child, into which the convex portion can be inserted, a first elastic body provided on one of the peripheral surfaces of the convex portion and the concave portion, and provided on the other side and engageable with the first elastic body The gripping means is a second elastic body disposed on the inner periphery of the receiving member.
[0007]
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 an example of a striking tool. An electric hammer 1 is provided with a cylinder 3 coaxially with a cylindrical housing 2 and reciprocatingly driven by a motor in the cylinder 3. The piston 4 is provided. Inside the cylinder 3, a striker 6 as a striker is accommodated in front of the piston 4 (left side in FIG. 1) through an air chamber 5 so as to be movable back and forth, and reciprocates with a predetermined stroke in conjunction with the piston 4. It is possible. A circular recess 7 is coaxially formed on the front surface of the striker 6, and a ring-shaped engagement portion 8 that slightly protrudes toward the axial center is provided at the front end of the inner peripheral wall of the recess 7. .
[0008]
On the other hand, a cylindrical tool holder 9 having a two-stage diameter through-hole 10 having a small diameter at the front is coaxially fixed to the front of the housing 2, and is used as an intermediate from the front between the tool holder 9 and the cylinder 3. The impact bolt 11 and the flanged sleeve 15 are accommodated so as to be movable back and forth. First, the impact bolt 11 includes a large-diameter portion 12 that can be loosely inserted into the tool holder 9 and a small-diameter portion 13 as a rear portion continuously provided behind the large-diameter portion 12. Has a bottomed hole 14 into which the rear end of the bit 23 can be loosely inserted. Further, the flanged sleeve 15 is provided with a through-hole 16 into which the small-diameter portion 13 of the impact bolt 11 can be loosely inserted, and an outer diameter around the through-hole 16 is engaged with the striker 6 at the rear end. A ring-shaped convex portion 17 that is slightly smaller than the inner diameter of the portion 8 protrudes, and the convex portion 17 can be loosely inserted into the concave portion 7 by the approach of the striker 6 and the flanged sleeve 15. An O-ring 18 serving as a first elastic body is mounted around the outer periphery of 17 so that it can interfere with the engaging portion 8 of the striker 6. Furthermore, an O-ring 19 is fitted as a second elastic body of the gripping means at a position slightly ahead of the O-ring 18 in the through-hole 16 of the flanged sleeve 15, and the impact bolt 11 loosely inserted into the through-hole 16. The small diameter portion 13 can be elastically gripped.
[0009]
The flanged sleeve 15 can be moved backward to the position of FIG. 1 where it abuts the front end of the cylinder 3, but the rear surface of the flanged sleeve 15 is externally attached to the front end of the cylinder 3, and the rear A coil spring 20 abutting against a plurality of stoppers 21, 21... Projecting in the circumferential direction on the inner surface of the housing 2 abuts to a forward position where the flanged sleeve 15 abuts on the rear end of the tool holder 9. It is energizing towards.
On the other hand, at the front end of the tool holder 9, a rod-shaped tool retainer 22 with a part of a circular cross-section cut away is mounted so as to be rotatable and orthogonal, and a bit is provided at a position where the cut-out portion faces the through hole 10. 23 can be loosely inserted into the through-hole 10, and if the tool retainer 22 is rotated in the loosely inserted state of the bit 23 to project a portion other than the notch into the through-hole 10, the portion is The bit 23 is mounted so as to be movable back and forth within a range in which the front and rear ends of the retaining recess 24 abut on the tool retainer 22 enter the retaining recess 24 formed in the axial direction on the upper surface.
[0010]
In the electric hammer 1 configured as described above, when the tip of the bit 23 is pressed against the ground or the like with the bit 23 attached to the tool holder 9 as described above during normal use, the rear end of the bit 23 is The impact bolt 11 is retracted by contacting the bottom of the bottomed hole 14 of the impact bolt 11. Then, the small diameter portion 13 of the impact bolt 11 passes through the through hole 16 of the flanged sleeve 15, and the rear surface of the large diameter portion 12 abuts against the flanged sleeve 15 to resist the biased sleeve 15 against the bias of the coil spring 20. To retreat. When the flanged sleeve 15 comes into contact with the front end of the cylinder 3, the small diameter portion 13 of the impact bolt 11 protrudes into the cylinder 3 as shown in FIG. 1. In this state, the motor is driven to reciprocate the striker 6 together with the piston 4. When moved, the striker 6 strikes the small diameter portion 13 of the impact bolt 11 when moving forward, and this is transmitted to the bit 23 via the impact bolt 11. Note that air holes 25, 25,... Are formed in the circumferential direction at the front end of the cylinder 3 to prevent the air chamber in front of the striker 6 from being blocked and the momentum of the striker 6 from being suppressed more than necessary. Yes. Further, at the position where the striker 6 abuts against the impact bolt 11, the engaging portion 8 of the striker 6 is located behind the O-ring 18 of the flanged sleeve 15, so there is no interference between them, and the reciprocation of the striker 6 is affected. Don't give.
[0011]
In a no-load state, for example, in a state where the tip of the bit 23 is not pressed against the ground or the like, the impact bolt 11 and the bit 23 are moved forward by the first idle driving of the impact bolt 11 accompanying the advance of the striker 6, and the coil spring 20 Due to the urging, the flange sleeve 15 also moves forward to a position where it comes into contact with the tool holder 9. At the same time, the striker 6 whose forward position is not restricted by the jumping out of the impact bolt 11 moves forward beyond a predetermined stroke, and the engaging portion 8 gets over the O-ring 18 of the flanged sleeve 15 as shown in FIG. To enter the recess 7. Therefore, the striker 6 is integrated with the flanged sleeve 15 by the engagement of the engaging portion 8 and the O-ring 18, and the interlock with the piston 4 is cut off. The cylinder 3 is provided with through holes 26, 26,... For preventing punching in the circumferential direction at positions where the striker 6 is not exposed to the air chamber 5 during the normal stroke of the striker 6. The through holes 26, 26,... Are opened at the position, and the air spring action by the air chamber 5 is also reduced, which contributes to the interruption of the interlock between the striker 6 and the piston 4.
[0012]
On the other hand, the bit 23 protruding in the first idle shot bounces back by abutting against the tool retainer 22 and pushes back the impact bolt 11 that has been advanced together. It is inserted into the through hole 16 of the attached sleeve 15 and press-fitted into the O ring 18. Since the force of the impact bolt 11 is weakened by this press-fitting and stops without penetrating the through-hole 16, the three parts of the striker 6, the flanged sleeve 15, and the impact bolt 11 are formed as shown in FIG. Integrate via 19. Therefore, even if the bit 23 further flutters back and forth due to these total weights, the amount of rearward movement is suppressed, and subsequent idle driving is effectively prevented. The
When the use of the electric hammer 1 is resumed, if the tip of the bit 23 is pressed against the ground or the like, the retracted bit 23 comes into contact with the impact bolt 11 to retract the three integrated parts. When the flanged sleeve 15 comes into contact with the front end of the cylinder 3 and stops, the impact bolt 11 retreats as it is, and the small diameter portion 13 penetrates the flanged sleeve 15 to press the striker 6, and the engaging portion 8 of the striker 6 is moved. In order to release the O-ring 18 and disconnect the striker 6 and the flanged sleeve 15, the striker 6 starts to interlock with the piston 4 again when the through holes 26 are closed by the striker 6.
[0013]
Thus, according to the said form, the connection means (the recessed part 7, the convex part 17, and the striker 6 which advanced ahead from the predetermined stroke between the striker 6 and the flanged sleeve 15 and the flanged sleeve 15 are connected elastically. While the engagement portion 8 and the O-ring 18) are provided, a gripping means (O-ring 19) capable of elastically gripping the small-diameter portion 13 of the impact bolt 11 is provided on the flanged sleeve 15, and the above-mentioned in an unloaded state. By integrating the striker 6, the flanged sleeve 15, and the impact bolt 11 in this way, the interlocking of the striker 6 and the suppression of the amount of rebounding of the impact bolt 11 are effectively realized. Can be reliably prevented.
In particular, here, the connecting means between the striker 6 and the flanged sleeve 15 is provided by the concave portion 7, the convex portion 17, the engaging portion 8, and the O-ring 18, and the gripping means for the impact bolt 11 in the flanged sleeve 15 is provided by the O-ring 19. By forming, the connecting means and the gripping means can be formed easily and compactly by rationally using the inner and outer circumferences of the flanged sleeve 15.
[0014]
In the above embodiment, the O-ring 18 is provided on the convex portion 17 of the flanged sleeve 15 and the engaging portion 8 is provided on the concave portion 7 of the striker 6, but these may be provided on the opposite sides. When the O-ring 18 is provided on the flanged sleeve 15 side, the O-ring 18 is not limited to the outer peripheral side of the flanged sleeve 15, and is provided in the through-hole 16 of the flanged sleeve 15 in the same manner as the O-ring 19 and at the front end of the striker 6. Instead of the recess 7, a projecting portion having the same diameter as the small diameter portion 13 of the impact bolt 11 is provided, and the projecting portion of the striker 6 projecting in an unloaded state is bounced back by an O-ring at the rear in the flanged sleeve 15. The eleven small-diameter portions 13 may be held by the O-rings in the front of the flanged sleeve 15.
Furthermore, the first and second elastic bodies are not limited to O-rings, and may be replaced with rubber balls or the like arranged in the circumferential direction.
And, as the connecting means and the gripping means, not only the elastic member separate from the flanged sleeve as the receiving member is used, but the receiving member is formed of an elastic body such as rubber, and the receiving member itself connects the striker. The meson may be gripped.
[0015]
【The invention's effect】
According to the first aspect of the present invention, by adopting the connecting means and the gripping means, the three parts of the striker, the receiving member, and the meson are integrated in an unloaded state, and the interlocking of the striker and the meson are separated. Suppression of the amount of rebounding backward is effectively realized, and idling can be reliably prevented.
According to the second aspect of the present invention, in addition to the effect of the first aspect, the connecting means is the convex part and the concave part, the first elastic body and the engaging part, and the gripping means is the inner part of the receiving member. By using the second elastic body disposed around the circumference, the connecting means and the gripping means can be easily and compactly formed by rationally using the inner and outer circumferences of the receiving member.
[Brief description of the drawings]
FIG. 1 is a partial longitudinal sectional view of an electric hammer.
FIG. 2 is a partial longitudinal sectional view of the electric hammer in an unloaded state.
FIG. 3 is a partial longitudinal sectional view of the electric hammer in an unloaded state.
[Explanation of symbols]
1 .... electric hammer, 2 .... housing, 3 .... cylinder, 4 .... piston, 6 .... striker, 7 .... concave, 8 .... engagement part, 9 .... tool holder, 11 .... impact bolt, 15 .... Sleeve sleeve, 18, 19, ... O-ring, 23 ... bit.

Claims (2)

A cylinder is provided in a cylindrical housing that is connected to a tool holder that can be inserted by inserting a bit into the tip. A piston that reciprocates by motor drive in the cylinder and a predetermined stroke via an air chamber in front of the piston. A striking element that moves forward and backward at the same time, and an intermediate element that can contact the rear end of the bit in front of the striking element, and a rear part of the intermediate element that can pass therethrough, and a cylinder whose rearward movement is restricted at a predetermined position. Can be moved back and forth, and when the bit is pushed in, the rear part of the intermediate member supported by the receiving member is struck by the striker, and the striking operation can be transmitted to the bit. The hitting tool
Between the receiving member and the striker, there is provided connecting means for allowing the striker advanced from the predetermined stroke to be elastically connected to the receiving member, while the receiving member is provided with a rear portion of the intermediate element inserted through the receiving member. In the first impact of the intermediate member by the impactor in an unloaded state, the impactor that has advanced with the withdrawal of the intermediate member from the receiving member is provided. An impact tool characterized in that it is connected to the receiving member via the connecting means, and a rear portion of the meson that bounces back after detachment from the receiving member is connected to the receiving member via the gripping means. . The connecting means is provided on a convex portion provided on the rear surface of the receiving member, a concave portion provided on the front surface of the striker, the concave portion into which the convex portion can be inserted, and a peripheral surface of any one of the convex portion and the concave portion. 2. The first elastic body and an engaging portion that is provided on the other side and engageable with the first elastic body, and the gripping means is a second elastic body that is disposed on the inner periphery of the receiving member. The hitting tool described in 1.

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