JP5154812B2 - Impact tool - Google Patents

Description

  The present invention relates to an impact tool such as an electric hammer or a hammer drill.

  As shown in Patent Document 1, a hammering tool such as an electric hammer or a hammer drill holds a bit at the front end in a housing and houses a tool holder in which a hammering mechanism is installed in the rear, and strikes the rotation of the motor. It is well known that it is converted into a reciprocating motion of a child, and a bit is directly struck by an impactor or indirectly via an intermediate such as an impact bolt.

JP 2004-167638 A

In such an impact tool, vibration may occur from the product itself as the bit is impacted. In particular, when the housing is divided into front and rear parts and connected by screws, rattling is likely to occur at the connection part, which causes vibration. The tool holder may be formed with a discharge hole for discharging air from the front of the striker when the striker reciprocates. In order to release the air discharged from the discharge hole to the rear. It is necessary to secure a gap between the tool holder side and the housing side behind the discharge hole. Therefore, the part on the tool holder abuts on the housing side in the gap portion during the hitting operation, which is also likely to cause vibration.
Due to such internal vibrations caused by the impact, there is a risk that the internal parts of the product will deteriorate and the service life may be shortened or the user may feel uncomfortable.

  Therefore, an object of the present invention is to provide a striking tool that can effectively reduce vibration inside a product due to striking.

In order to achieve the above object, the invention described in claim 1 is characterized in that a motor is driven in a housing formed by connecting a cylindrical front housing and a rear housing divided into front and rear by screws, and driving the motor. And a striking tool accommodating a striking mechanism capable of striking a bit attached to the front end of the front housing, wherein a sleeve through which a screw passes coaxially at a connecting portion between the front housing and the rear housing is connected to the front housing. While the housing is accommodated across the rear housing, an inner housing that supports the output shaft of the motor is provided in the housing, and the flange protruding from the periphery of the inner housing is in contact with the outer periphery of the sleeve. It is characterized by being sandwiched between a front housing and a rear housing .
In addition to the object of the first aspect, the invention described in claim 2 is characterized in that the sleeve is made of metal in order to reduce vibration more effectively by the sleeve.
According to a third aspect of the present invention, in addition to the object of the first or second aspect , a tool holder in which a bit is held at the front end and a striking mechanism is installed in the rear housing is accommodated in the front housing. In order to reduce vibration between the tool holder and the front housing, the tool holder side is moved to the front housing side at the rear of the discharge hole in order to reduce vibration between the tool holder and the front housing. In addition to this, a ventilation path through which air discharged from the discharge hole can pass is formed between the tool holder side and the front housing side.
Here, the “tool holder side” and the “front housing side” indicate not only the tool holder and the front housing itself, but also the parts that are assembled integrally therewith.
According to a fourth aspect of the present invention, in addition to the object of the third aspect , an intermediate shaft for transmitting the rotation of the motor to the tool holder is supported between the motor and the tool holder. In order to effectively reduce the vibration, at least two bearings supporting the front end of the intermediate shaft are arranged in the axial direction.

According to the first aspect of the present invention, the use of the sleeve at the connecting portion between the front housing and the rear housing effectively reduces vibration inside the product during use, shortening the life of the parts and feeling of use. Is suppressed. In particular, the integrity of the front housing and the rear housing is improved, and an effective structure is achieved by reducing vibration.
Further, the integrity of the front housing, the rear housing, and the inner housing is enhanced.
According to the second aspect of the invention, in addition to the effect of the first aspect, a sleeve with high dimensional accuracy can be used, which is effective in reducing vibration.
According to the invention described in claim 3 , in addition to the effect of claim 1 or 2 , the rattling between the tool holder side and the front housing side is ensured while ensuring the passage of air outside the tool holder. Without it, the vibration in the part can be reduced.
According to the fourth aspect of the invention, in addition to the effect of the third aspect , resonance at the time of impact is suppressed, and vibration at the intermediate shaft is effectively suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial longitudinal sectional view of a hammer drill which is an example of a striking tool of the present invention. A housing of the hammer drill 1 includes a front housing 2 that houses a tool holder 20 having a striking mechanism therein, and a front housing thereof. 2 and the rear housing 3 that houses the motor 4 at the rear (right side in FIG. 1), and the output shaft 5 of the motor 4 is pivotally supported by the inner housing 6 assembled in the front housing 2. 2 protrudes inside.
As shown in FIG. 2 (A), the front housing 2 and the rear housing 3 are formed by four screws 7, 7,... Screwed into the rear housing 3 from the front housing 2 side at the four corners around the cross section. Here, the recesses 8 and 9 that are coaxial with the screw 7 are formed on the opposing surfaces of the front housing 2 and the rear housing 3, and are made of metal across the recesses 8 and 9. A sleeve 10 is accommodated, and each screw 7 has a structure that penetrates the sleeve 10 and is screwed into the rear housing 3.

  In this connected state, the flanges 11, 11... Projecting from the periphery of the inner housing 6 are in contact with the outer periphery of the sleeve 10 and are sandwiched between the front housing 2 and the rear housing 3. With this configuration, the integrity of the front housing 2, the rear housing 3, and the inner housing 6 is enhanced. Reference numeral 12 denotes an O-ring that is accommodated in a groove 13 that is recessed in the peripheral surface of the inner housing 6 and that abuts against the inner peripheral surface of the front housing 2 in the assembled state.

On the other hand, in the front housing 2, the intermediate shaft 14 is supported in parallel with the output shaft 5, and the first gear 15 provided at the rear is engaged with the output shaft 5. The intermediate shaft 14 is pivotally supported by a ball bearing 16 whose rear end is held by the inner housing 6, and its front end is pivotally supported by a pair of ball bearings 17 and 17 that are coaxially arranged and held by the front housing 2 in the axial direction. Has been.
In addition, a second gear 18 is mounted in front of the intermediate shaft 14 so as to be rotatable separately from the intermediate shaft 14 and slidable in the axial direction, and is supported in parallel with the intermediate shaft 14 above the intermediate shaft 14. It meshes with the third gear 19 of the tool holder 20. Further, a boss sleeve 21 is externally mounted on the rear side of the intermediate shaft 14 and in front of the first gear 15 so as to be rotatable separately from the intermediate shaft 14. A swash bearing 22 having an inclined axis is rotatably fitted on the outer periphery of the boss sleeve 14, and a connecting arm 23 protruding from the upper portion of the swash bearing 22 is loosely inserted into the tool holder 20 from behind. The piston cylinder 24 is pivotally attached to the rear end. The piston cylinder 24 accommodates a striker 26 as a striker through an air chamber 25 so as to be movable back and forth.

  In addition, a clutch 27 is provided between the second gear 18 and the boss sleeve 21 in the intermediate shaft 14. The clutch 27 is splined to the intermediate shaft 14 so as to be integrally rotatable and slidable in the axial direction. The front surface can be engaged with the second gear 18 and the rear surface can be engaged with the boss sleeve 21, respectively. 1 and the second gear 18 are urged to a position shown in FIG. 1 by retreating together with the second gear 18 and simultaneously meshing with the second gear 18 and the boss sleeve 21 by a coil spring 28 sheathed on the intermediate shaft 14. ing. The second gear 18 and the clutch 27 are rotated by the front housing 2 and a switching plate (not shown) that is slidable in parallel with the intermediate shaft 14 by being engaged with the clutch 27, as in Patent Document 1 shown in the background art. A sliding lever that is provided so as to be operable and has a switching plate and two eccentric pins that are engaged with the second gear 18 according to the rotational position can be arbitrarily slid.

The tool holder 20 is pivotally supported on the inner housing 6 by the bearing sleeve 29, while the front portion is pivotally supported by the needle bearing 30 on the small diameter portion 2 a in front of the front housing 2. A holder portion 33 to which a bit 32 can be inserted and attached from the front end is connected to the front portion of the tool holder 20 from the front end, and an impact bolt 34 serving as an intermediate element can be moved back and forth behind the bit 32 in the holder portion 33. Is housed in.
In addition, as shown in FIG. 3, the tool holder 20 also includes a receiving ring 35 and a washer 36 that restrict the retracted position of the impact bolt 34, and an O-ring 38 that can grip the front end of the striker 26 when idling. A grip ring 37 provided on the inner periphery is accommodated in a state in which movement in the axial direction is restricted by the rear end of the holder portion 33 and the stopper ring 39. Reference numerals 40 and 40 denote discharge holes that are formed in the tool holder 20 at the position of the stopper ring 39 and allow the second air chamber 41 in front of the striker 26 to communicate with the outside of the tool holder 20.

  On the other hand, the third gear 19 that is sheathed on the tool holder 20 is a coil spring that is sheathed on the tool holder 20 with the washer 43 whose forward movement is restricted by the locking ring 42 at the rear end of the discharge hole 40. By being biased rearwardly by 44 and engaging with a flange 45 that is provided at an intermediate position of the tool holder 20 at the rear position, the tool holder 20 and the tool holder 20 can rotate together. The washer 43 is in contact with the rear end 47 of the holding sleeve 46 of the needle bearing 30 that is locked to the rear end of the small-diameter portion 2a, and has an arcuate notch 48, as shown in FIG. 48 are formed at equal intervals. Therefore, the outside of the tool holder 20 outside the discharge hole 40 is in communication with the rear side by a ventilation path formed between the rear end 47 of the holding sleeve 46 and the notch 48 of the washer 43.

  In the hammer drill 1 configured as described above, when the motor 4 is driven in the state shown in FIG. 1 with the bit 32 attached to the tool holder 20, the intermediate shaft 14 rotates, and the rotation is caused by the clutch 27 and the second gear 18. This is transmitted to the tool holder 20 via the third gear 19 and rotates the bit 32, while also being transmitted to the boss sleeve 21 connected to the clutch 27. Therefore, the swash bearing 22 swings and the connecting arm 23 reciprocates the piston cylinder 24. By this operation, the striker 26 in the piston cylinder 24 reciprocally moves and strikes the impact bolt 34 with which the rear end of the bit 32 abuts. Therefore, the hammer 32 is transmitted to the bit 32 in addition to rotation. Become.

Next, when the clutch 27 is separated from the boss sleeve 21 while being engaged with the second gear 18 by operating the switching lever, and the motor 4 is driven in this state, the rotation of the intermediate shaft 14 causes the clutch 27 and the second and second gears to rotate. It is transmitted to the tool holder 20 through the three gears 18 and 19. On the other hand, since the rotation is not transmitted to the boss sleeve 21 disengaged from the clutch 27, the piston cylinder 24 does not reciprocate. Therefore, a drill mode in which the bit 32 only rotates is set.
When only the second gear 18 is separated from the clutch 27 by operating the switching lever, the rotation of the intermediate shaft 14 is not transmitted to the second gear 18 and the third gear 19 and the tool holder 20 do not rotate. On the other hand, since the boss sleeve 21 is rotated to reciprocate the piston cylinder 24, the hammer mode in which only the impact is transmitted to the bit 32 is set.

When used in each of these operation modes, an impact due to rotation or impact is transmitted even inside the hammer drill 1, but a sleeve 10 is externally attached to the screw 7 that connects the front housing 2 and the rear housing 3. Therefore, rattling is unlikely to occur in the X-axis and Y-axis directions (left and right and up and down directions in FIG. 2), and vibrations in these directions are suppressed.
On the other hand, the tool holder 20 provided with the striking mechanism is pivotally supported in a state in which the washer 43 is in contact with the holding sleeve 46 on the front housing 2 side, so that the tool holder 20 swings in the Z-axis direction (the axial direction of the tool holder 20). Sticking is unlikely to occur, and vibration in that direction is suppressed.
In addition, since the front end of the intermediate shaft 14 is supported by the two ball bearings 17 and 17 to increase the rigidity, the resonance in the X-axis and Y-axis directions, particularly when the swash bearing 22 is swung, is generated. Effectively suppressed.

Thus, according to the hammer drill 1 of the said form, the sleeve 10 which the screw | thread 7 penetrates coaxially in the front housing 2 and the rear housing 3 in the connection part of the front housing 2 and the rear housing 3 was accommodated. Thus, the vibration inside the product during use is effectively reduced. Therefore, shortening of the component life and deterioration of the feeling of use are suppressed.
In particular, since the sleeve 10 is made of metal, the sleeve 10 with high dimensional accuracy can be used, which is effective in reducing vibration. Further, since the sleeve 10 is accommodated across the front housing 2 and the rear housing 3, the integrity of the front housing 2 and the rear housing 3 is improved, and an effective structure is achieved by reducing vibration.

On the other hand, the washer 43 on the tool holder 20 side is brought into contact with the holding sleeve 46 on the front housing 2 side behind the discharge hole 40, and air discharged from the discharge hole 40 is interposed between the washer 43 and the holding sleeve 46. Since the air passage that can pass is formed, it is possible to reduce the vibration of the part by eliminating the rattling between the washer 43 and the holding sleeve 46 while ensuring the passage of air outside the tool holder 20. ing.
Further, since two ball bearings 17 that support the front end of the intermediate shaft 14 are arranged in the axial direction, resonance at the time of impact is suppressed, and vibration at the intermediate shaft 14 is effectively suppressed.
As described above, by adopting a plurality of vibration suppressing structures in the main portions of the front and rear housings 2 and 3, the tool holder 20, and the intermediate shaft 14, the vibration suppressing action is exhibited synergistically.

In the above embodiment, the sleeve is made of metal, but it may be made of rubber or synthetic resin. Of course, the number and arrangement of screws and sleeves are not limited to the above-described form, and may be appropriately changed according to the shape of the housing and the required rigidity.
Furthermore, the air passage is formed by a notch provided on the outer periphery of the washer, but it may be replaced with a groove or a through hole provided in the outer surface, or a groove or a through hole may be provided on the holding sleeve side, not on the washer side. It may be provided to ensure ventilation. The tool holder side and the front housing side that form the air passage are not limited to the washer and the holding sleeve. For example, if there is no holding sleeve, the tool is formed by directly forming a notch or a through hole in the front housing. The design can be changed in accordance with the structure of the impact tool, such as ensuring ventilation while maintaining contact with the holder side.
In addition, the bearing of the intermediate shaft can be changed by increasing the number of ball bearings and adopting other bearings such as needle bearings and bearing sleeves. It is also conceivable to increase rigidity by increasing the axial length of the bearing. Further, it is not hindered to adopt the same structure for the bearing on the rear end side of the intermediate shaft.

On the other hand, in the above embodiment, in addition to the connection portion between the front housing and the rear housing, it is an example in which a vibration suppressing structure is adopted between the tool holder and the front housing and the front end of the intermediate shaft. Either or both of the vibration suppressing structures between the front housing and the front end of the intermediate shaft may be omitted.
In addition, the present invention is not limited to the hammer drill but can be applied to other impact tools such as an electric hammer.

It is a partial longitudinal cross-sectional view of a hammer drill. (A) is an AA line sectional view, (B) is a CC line sectional view. It is an enlarged view of the B section. It is explanatory drawing of a washer.

Explanation of symbols

  1 .... Hammer drill, 2 .... Front housing, 3 .... Rear housing, 4 .... Motor, 5 .... Output shaft, 6 .... Inner housing, 7 .... Screw, 8, 9 ...., Recess, 10 .... Sleeve 11, Flange 14, Intermediate shaft 15, First gear 16, 17 Ball bearing 18, Second gear 19, Third gear 20, Tool holder 21, · Boss sleeve, 22 · · Swash bearing, 24 · · Piston cylinder, 26 · · Striker, 27 · · Clutch, 32 · · Bit, 33 · · Holder, 34 · · Impact bolt, 40 · · Discharge hole, 41・ ・ Second air chamber, 43 ・ ・ Washer, 48 ・ ・ Notch.

Claims (4)

In a housing formed by connecting a cylindrical front housing and a rear housing, which are divided into front and rear, by a screw, a motor and a hammer that operates by driving the motor and can hit a bit attached to the front end of the front housing A striking tool containing a mechanism,
While connecting the front housing and the rear housing, the sleeve through which the screw passes coaxially is accommodated across the front housing and the rear housing ,
An inner housing that supports the output shaft of the motor is provided in the housing, and a flange that protrudes from a peripheral edge of the inner housing is in contact with the outer periphery of the sleeve, and the front housing and the rear housing A striking tool characterized in that it is held between.   The impact tool according to claim 1, wherein the sleeve is made of metal. In the front housing, a bit holder is held at the front end, a tool holder in which a striking mechanism is installed in the rear is accommodated, and an air discharge hole is formed in front of the striking element of the striking mechanism in the tool holder. An air passage through which the air discharged from the discharge hole can pass between the tool holder side and the front housing side between the tool holder side and the front housing side at the rear of the discharge hole the impact tool according to claim 1 or 2, characterized in that the formed. An intermediate shaft that transmits the rotation of the motor to the tool holder is supported between the motor and the tool holder, and at least two bearings that support the front end of the intermediate shaft are arranged in the axial direction. The impact tool according to claim 3 .

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