JP6022318B2 - Hammer drill - Google Patents

Description

  The present invention relates to a hammer drill for performing a hammer operation on a workpiece.

As shown in Patent Document 1 below, a hammer drill having a tool holder for mounting a bit is known.
The tool holder contains an impact bolt for hammering the bit, a striker for moving the impact bolt, and a front portion of a cylinder containing a piston for moving the striker.
Further, a bevel gear that can rotate around the cylinder by receiving a driving force from the intermediate shaft is disposed on the rear end side of the tool holder. The bevel gear is fixed to the rear end portion of the tool holder and rotates the tool holder. With the rotation of the tool holder, the bit or the like is also rotated to perform a drilling operation.
The bevel gear in such a hammer drill is positioned (regulation of movement in the front-rear direction, which is the direction of the rotation axis) by a gear housing (barrel) via a buffer member as appropriate.

JP 2006-136972 A

In the above hammer drill, since the movement in the front-rear direction is regulated by the gear housing, if the tool holder is slightly displaced in the front-rear direction due to the impact reaction force, the bevel gear is also displaced in the front-rear direction, relative to the intermediate shaft. The movement of the bevel gear and the intermediate shaft will shift and the operation will temporarily deteriorate, and the accumulation of displacement will affect the life such as wear of the bevel gear and the intermediate shaft. Effect.
Therefore, the main object of the present invention is to provide a hammer drill having a bevel gear or the like that has a good operation and a long life.

In order to achieve the above object, the invention according to claim 1 is arranged adjacent to the bevel gear, a crank housing for accommodating a crank, a tool holder for mounting a bit, a bevel gear for rotating the tool holder, and the like. A sleeve member disposed adjacent to the crank housing, and the sleeve member is fixed in the axial direction of the tool holder by being sandwiched between the crank housing and the barrel. And a cam member detachably engageable with the bevel gear, the outer diameter of the cam member is the same as the inner diameter of the sleeve member, and a groove is provided in the cam member, A slide plate for switching engagement / disengagement of the cam member with respect to the bevel gear is hung on the groove. The notch to avoid slide plate is provided and is characterized in.
According to a second aspect of the present invention, in the above invention, the sleeve member has a flange sandwiched between the crank housing and the barrel, and a rear end portion of the sleeve member is located on a front side of the bevel gear. It is characterized by being adjacent.
The invention described in claim 3 is characterized in that, in the above-mentioned invention, the sleeve member is press-molded.
According to a fourth aspect of the invention, in the above invention, the sleeve member has a protrusion, said the crank housing, Ru der those characterized by a recess for receiving said projection is provided .

Of the present invention, according to the invention described in claim 1, is fixed in the axial direction of the tool holder in the sleeve member is positioned adjacent the bevel gear is interposed between said barrel and said crank housing, further The outer diameter of the cam member that can be engaged with and disengaged from the bevel gear is the same as the inner diameter of the sleeve member (the outer diameter of the former is slightly smaller than the inner diameter of the latter), and the groove provided around the cam member has a bevel gear of the cam member. and takes slide plate to switch the disengaged against, because the sleeve member is provided notch to avoid slide plate, it is possible to reliably prevent the back-and-forth movement of the bevel gear, actuation of the bevel gear or its peripheral member ( it can also be good as provided sleeve member per including disengagement of the cam member and the bevel gear), a length to prevent their wear Service life can be achieved, and the cam member and the bevel gear can be easily performed accurate assembly of the cam member and a bevel gear and temporarily fixed, the sleeve per cam member for switching the presence or absence of the tool holder rotating member Ru can be operable even when the provided an effect that.
According to the invention of claim 2, in the above invention, the sleeve member has a flange sandwiched between the crank housing and the barrel, and the rear end portion of the sleeve member is adjacent to the front side of the bevel gear. In addition to the above effects, when the bevel gear is arranged inside the crank housing, the movement of the bevel gear in the front-rear direction can be appropriately suppressed, and the flange comes out forward so that the bevel gear or the like is temporarily fixed. There is an effect that can be performed appropriately.
Further, according to the invention described in claim 3, in the above invention, since the sleeve member is press-molded, in addition to the above effects, the sleeve member is hardened so that the movement of the bevel gear in the front-rear direction is more appropriately performed. There is an effect that it can be suppressed.
In addition, according to the invention described in claim 4, in the above invention, since the sleeve member has a protrusion, and the crank housing that houses the sleeve member is provided with a recess for receiving the protrusion, the sleeve member is a bevel gear. and it is possible to prevent the thus rotated together with the cam member, it is possible to ensure even correct operation as provided sleeve member, to bring out the effects of.

It is a center longitudinal cross-sectional view of the hammer drill which concerns on this invention. It is an enlarged view of the center part in FIG. It is an enlarged view of the receiving part A periphery in FIG. It is a front view of the crank housing in FIG. 1, or its peripheral member. FIG. 2 is a partially exploded perspective view of a crank housing or its peripheral members in FIG. 1.

  Hereinafter, embodiments of the present invention and modifications thereof will be described with reference to the drawings as appropriate.

FIG. 1 is a longitudinal sectional view of a hammer drill 1, and FIG. 2 is an enlarged view of a central portion of FIG.
The hammer drill 1 has a main body housing 2 that forms an outline of the hammer drill 1, a bit 6 that is detachably attached to a front end region of the main body housing 2 (on the left side in FIG. 1 in the horizontal direction) via a tool holder 4, and the opposite side. It has a hand grip 8 formed by the operator formed at the rear of the main body housing 2.
The handgrip 8 is provided with a switch lever 9 that can be pushed backward.

The motor 10 is accommodated in the lower part of the main body housing 2, and the motor rotating shaft 12 is placed in the lower part of the gear housing 14 fixed at the upper center of the main body housing 2.
A horizontal driven gear 16 meshes with the upper part, which is the tip of the motor rotating shaft 12. The driven gear 16 is fixed around the lower portion of the crankshaft 20 having a crank protrusion 18 on the periphery of the upper end portion. A crankshaft 20 as a crank is mounted in the gear housing 14 so as to be rotatable about the vertical direction as a rotating shaft. Further, in the gear housing 14, a crank housing 22 made of a magnesium alloy having a cylindrical shape with the front portion being an axial direction in the front-rear direction and the rear portion being an axial direction in the vertical direction is fixed. The upper part of the crankshaft 20 enters the rear cylinder part of the crank housing 22, and a part of the crankshaft 20 is pivotally supported by the rear cylinder part of the crank housing 22 via the crank bearing 24.
An intermediate shaft unit 25 that is pivotally supported between the gear housing 14 and the crank housing 22 is disposed on the opposite side (front side) of the driven gear 16 with respect to the motor rotation shaft 12. The intermediate shaft unit 25 meshes with the motor rotating shaft 12 and a bevel gear 26 described later.

The crank protrusion 18 of the crankshaft 20 is rotatably inserted into a hole formed in the rear part of the rod 30 facing in the front-rear direction.
The front cylinder portion of the crank housing 22 is provided with a rear portion of a cylindrical cylinder 32 whose axial direction is the front-rear direction, and the front portion of the rod 30 is located in the cylinder 32.
The rear end portion of the cylinder 32 is received by a receiving portion A formed on an inner wall along the vertical direction of the crank housing 22. The inner wall is formed between the front cylinder part and the rear cylinder part of the crank housing 22.
The receiving portion A and the outer peripheral edge of the rear end of the cylinder 32 are rounded, and more specifically, as shown in FIG. 3, the corner portion of the receiving portion A is round (as if a sharp corner is filled). The corners (outer peripheral edges of the rear end) of the cylinder 32 are chamfered. With respect to the roundness of the corner of the receiving part A, the chamfered surface of the cylinder 32 whose rear end is located on the receiving part A has escaped, and the corner of the cylinder 32 has an escape part E with respect to the corner of the receiving part A. It has come to have.

A disc-shaped piston 33 having an outer diameter similar to the inner diameter of the cylinder 32 is slidably inserted in the same axial direction in an airtight state. Connected to the rear.
A striker 34 that is slidable in an airtight manner like the piston 33 is housed in the cylinder 32 and in front of the piston 33.
An air chamber 35 is formed between the piston 33 and the striker 34.
Vent holes 36, 36... Are opened on the top and bottom of the cylinder 32.
A rod-like impact bolt 37 having a swollen head (front) is fixed to the front portion of the striker 34, and the base end (rear end) of the mounted bit 6 is located on the front side of the impact bolt 37.
The tool holder 4 extends so as to surround the bit 6 base portion, the impact bolt 37, and the front portion of the cylinder 32, and the tool holder 4 is positioned relative to the tool holder 4 front portion that houses the bit 6 base portion and the head of the impact bolt 37. The rear part is expanded in diameter both inside and outside.

A part of the rear part of the tool holder 4 whose diameter has been enlarged enters the front part of the crank housing 22, and the rear end part of the tool holder 4 enters a cylindrical bevel gear 26 whose axial direction is the front-rear direction. The bevel gear 26 accommodates the rear end portion of the tool holder 4 in the crank housing 22, and can be rotated around the tool holder 4 or on the rear side by the intermediate shaft unit 25.
As shown in FIGS. 4 and 5, on the front side of the bevel gear 26, a spline ring 38 as a cam member can be moved back and forth on the outer wall of the tool holder 4, and the tool holder can be moved at any front and back positions within the moving range. 4 is rotatably mounted together. The spline ring 38 is connected to a slide plate 39 along the front-rear direction. When the slide plate 39 is on the front side, the spline ring 38 is separated from the bevel gear 26, and the rotation of the bevel gear 26 by the motor 10 or the intermediate shaft unit 25 is splined. It is not transmitted to the ring 38 or the tool holder 4. On the other hand, the spline ring 38 is engaged with the bevel gear 26 when the slide plate 39 is pulled from the front side to the rear side by the operation unit (not shown) (the state shown in FIGS. 1 and 2). The drive force reaches the tool holder 4 through the intermediate shaft unit 25, the bevel gear 26, and the spline ring 38.

The spline ring 38 and the bevel gear 26 are engaged by engagement of teeth 38a, 38a,... Formed on the outer peripheral surface of the spline ring 38 and teeth 26b, 26b, formed on the inner peripheral surface of the front portion 26a of the bevel gear 26. Stopped.
A groove 38b is provided in the center of the outer peripheral surface of the spline ring 38 in the front-rear direction, and claws 39a and 39a at the front portion of the slide plate 39 are placed in the groove 38b. In FIG. 5, only the spline ring 38 and the slide plate 39 are shown in a connected state.

Further, a sleeve member 40 formed in a ring shape by press molding is arranged outside the spline ring 38.
The upper part of the sleeve member 40 has a notch 40a on the front side and only a thin arc 40b at the rear. Similarly, the lower portion of the sleeve member 40 has a cutout portion 40c and an arc portion 40d. Further, on both sides of the arc portions 40b and 40d, relatively arcuate arc portions 40e and 40e that connect them are disposed. A single ring portion is formed at the rear portion of the sleeve member 40 by the arc portions 40b, 40d, 40e, and 40e.
At the front end portion of the sleeve member 40, flanges 40f and 40g are formed that extend from the rear portion except for the cutout portions 40a and 40c to form a surface along the vertical direction. A small protrusion 40h that protrudes to the side is provided at the outer peripheral central portion of the flange 40f, and a protrusion 40i that protrudes to the side is provided at the outer peripheral central portion of the flange 40g.

On the other hand, the rear portion 26c of the bevel gear 26 is a cylindrical portion having a smaller diameter than the front portion 26a, and a step 26d is formed between the front portion 26a and the rear portion 26c.
And the sleeve member 40 is arrange | positioned in the state in which the rear part (arc part 40b, 40d, 40e, 40e) exists in the front side of the front part 26a (base of the teeth 26b, 26b ...) of the bevel gear 26. At this time, the flanges 40f and 40g of the sleeve member 40 stand on the front upper side of the spline ring 38 moved rearward.
When the slide plate 39 is passed through the notch 40a of the sleeve member 40 and the slide plate 39 is pulled most rearward (the state shown in FIGS. 1 and 2), the claw 39a comes into contact with the arc 40b, and the spline The teeth 38a, 38a,... Of the ring 38 mesh deeply with the teeth 26b, 26b,.

Further, on the rear side of the head portion of the impact bolt 37, a ring 41 and a rubber ring 42 having an axial direction in the front-rear direction are disposed so as to surround the impact bolt 37.
A cylindrical slide sleeve 44 that can slide back and forth is provided from the rear side of the rubber ring 42 to the periphery of the front end edge of the cylinder 32.
The front end portion of the slide sleeve 44 has a ring-shaped wall portion extending in the vertical direction so as to receive the rubber ring 42, and the front inner diameter excluding the front end portion of the slide sleeve 44 is the same as the outer diameter of the cylinder 32. Thus, the rear inner diameter of the slide sleeve 44 is larger than the front part.

A small spring 46, which is a first elastic body exhibiting an elastic action in the front-rear direction, is housed between the inner wall of the slide sleeve 44 and the outer wall of the cylinder 32, which is the rear portion of the slide sleeve 44 having an enlarged diameter. .
The front end of the small spring 46 is in contact with a small wall that extends in the up-down direction provided by expanding the diameter, and the rear end of the small spring 46 is stopped by a ring-shaped circlip 48 whose axial direction is the front-rear direction. The circlip 48 is fixed by entering a groove (step) having a front-rear width similar to the thickness of the circlip 48 provided around the outer wall of the cylinder 32.
A metal washer 50 hardened by heat treatment is fixed to the rear side of the circlip 48. The washer 50 is fixed by entering a groove having a front-rear width similar to the front-rear thickness of the washer 50 provided on the outer wall of the cylinder 32. The rear surface of the groove (the surface along the vertical direction) forms a step with respect to the cylinder outer wall surface behind it. The groove for the circlip 48 and the groove for the washer 50 are continuous here. Note that there is a difference in the depth of each groove (the groove for the washer 50 is shallower).
On the rear side of the washer 50, a slide ring 52 that can slide in the front-rear direction on the outer wall of the cylinder 32 is provided.
On the rear side of the slide ring 52, a spring 54 as a second elastic body that exhibits an elastic action in the front-rear direction is provided around the cylinder 32, and fixed on the rear side of the spring 54 in the same manner as the circlip 48. A ring 56 is arranged.

On the rear side of the ring 56, a metal circlip 58 (a circumferential member provided around the cylinder 32 body) fixed in the same manner as the circlip 48 is provided.
A part of the inner wall along the vertical direction of the crank housing 22 is in contact with the rear side of the circlip 58, and a receiving part B that receives the cylinder 32 via the circlip 58 is formed by a part of the inner wall. It will be.
The receiving portion B is formed as a step portion corresponding to the circlip 58 by denting the inner portion of the inner wall backward from the outside by a depth similar to the thickness of the circlip 58.
The front part of the front cylinder part of the crank housing 22 is expanded in diameter both inside and outside with respect to the rear part of the front cylinder part, and the inner wall connects the front part and the rear part of the front cylinder part generated by the expansion. A vertical wall. The rear part of the cylinder 32 is in the rear part of the front cylinder part of the crank housing 22, and the receiving part B is arranged at the front end of the rear part of the front cylinder part of the crank housing 22.

On the other hand, in the front part of the main body housing 2 and around the center part of the tool holder 4, a barrel 60 that covers the center part is provided. The barrel 60 is fixed to the main body housing 2 and the front end opening of the crank housing 22.
The sleeve member 40 is fixed so as not to move in the front-rear direction (the direction of the rotation axis of the tool holder 4) by being sandwiched between the crank housing 22 and the barrel 60.
More specifically, it is fixed as follows. That is, in the front end opening portion 22a of the crank housing 22, an opening step portion 22b as a step with respect to the front side is provided by slightly reducing the rear diameter with respect to the front diameter. Further, a reduced diameter portion 60 a that is slightly reduced in diameter so as to enter the inner periphery of the front end opening 22 a of the crank housing 22 is provided at the rear end portion of the barrel 60. The front side of the reduced diameter portion 60 a is a surface along the vertical direction, and is arranged to receive the front end opening 22 a of the crank housing 22. The flanges 40 f and 40 g of the sleeve member 40 are sandwiched between the rear end surface along the vertical direction of the reduced diameter portion 60 a of the barrel 60 and the opening step portion 22 b of the crank housing 22.
In the crank housing 22, concave portions (not shown) having the same shape as these are provided at positions corresponding to the small projections 40 h and the projections 40 i so that the small projections 40 h and the projections 40 i can be inserted into the concave portions. Yes.

An operation example of such a hammer drill 1 will be described.
When the operator pushes the switch lever 9 of the handgrip 8 to turn on the power, the motor 10 operates to rotate the motor rotating shaft 12, and the rotation is transmitted through the intermediate shaft unit 25 to the bevel gear. 26. Depending on the state of the slide plate 39, the tool holder 4 does not rotate unless the spline ring 38 is applied to the bevel gear 26, and the internal bit 6 or the like does not rotate. On the other hand, when the spline ring 38 is applied to the bevel gear 26, the tool holder 4 also rotates through the spline ring 38, and the bit 6 and the like inside thereof also rotate.

Further, the rotation of the motor rotating shaft 12 is transmitted to the crankshaft 20 via the driven gear 16. The crankshaft 20 and the rod 30 convert rotational motion into reciprocating motion. The piston 33 at the tip of the rod 30 reciprocates in the cylinder 32.
The piston 33 pushes the air in the air chamber 35 by moving forward, and pulls the air in the air chamber 35 by moving backward.
If the bit 6 is not pushed rearward from the outside and the impact bolt 37 and the striker 34 in the tool holder 4 are positioned at the front part of the operation range of the tool holder 4, the vent holes 36, 36,. Therefore, the air in the air chamber 35 escapes from the vent holes 36, 36... And the impact bolt 37 and the bit 6 do not reciprocate to prevent idle driving. At this time, the small spring 46 and the spring 54 are in a compressed state.

On the other hand, when the bit 6 is pushed backward by a reaction force or the like from the workpiece, and the impact bolt 37 and the striker 34 are located at the rear part of the operation range, the vent holes 36, 36. Therefore, the striker 34 is pushed and pulled through the air in the air chamber 35, and the impact bolt 37 and the bit 6 reciprocate to perform a hammer operation.
When the bit 6 is pushed rearward, the small spring 46 and the spring 54 are further compressed through the impact bolt 37, the ring 41, the rubber ring 42, and the slide sleeve 44, and the pressing force is buffered by an elastic action. In the maximum pressing state, the front end of the cylinder 32 hits the inner wall (the inner side of the ring-shaped portion) of the front end portion of the slide sleeve 44.
When the bit 6 is pushed rearward, the slide sleeve 44 moves rearward, pushes the slide ring 52, and the spring 54 is compressed. When the bit 6 returns to the front, the slide ring 52 returns to the front together with the slide sleeve 44 due to the action of the spring 54 or the like. This backward movement and forward return are repeated for each impact, and the slide ring 52 hits the washer 50 each time the forward return is made. The washer 50 can prevent the slide ring 52 from directly hitting the circlip 48, and can reduce the load on the circlip 48 for fixing the small spring 46, so that the circlip 48, the slide ring 52, etc. The degree of progress of wear can be reduced. Further, since the washer 50 is made of metal, the slide ring 52 can be firmly received in a high strength state, and since the washer 50 is cured by heat treatment, the hardness of the washer 50 is further increased. The load and wear of the circlip 48 and the like can be reduced. In addition, since a step is provided on the outer wall of the cylinder 32 on the rear side of the washer 50 (rear inner surface portion), the washer 50 can be supported by the step, further reducing the load and wear on the circlip 48 and the like. Can be planned.

  Further, even if the pressing force, striking stress or reaction force thereof is buffered by the small spring 46, the spring 54, the rubber ring 42, etc., a backward force may act on the cylinder 32. Even if such a force is applied, the cylinder 32 can be received by the two receiving portions A and B separated in the front and rear in the crank housing 22.

Since the flanges 40f and 40g in the sleeve member 40 that contacts the front end portion (thick portion) of the bevel gear 26 are sandwiched between the crank housing 22 and the barrel 60, they are fixed so as not to move in the front-rear direction. Even if the holder 4 receives a forward force, it is possible to prevent the bevel gear 26 from shifting, and it is possible to prevent these malfunctions and wear due to misalignment between the bevel gear 26 and the intermediate shaft unit 25.
When the hammer drill 1 is manufactured, when assembling the crank housing 22 and its members, the sleeve member 40 is temporarily assembled in front of the front portion 26a of the bevel gear 26, and the arc portions 40b, 40d, 40e, By temporarily assembling a spline ring 38 with a slide plate 39 inside 40e (ring part), the sleeve member 40 is gently engaged with the bevel gear 26 and the spline ring 38, and the bevel gear 26, sleeve member 40, The spline ring 38 can be temporarily fixed at a desired position (position where correct assembly can be performed), and correct assembly of the crank housing 22 and the like is easier than when the sleeve member 40 is not provided and temporary fixation is not performed. It becomes easier and more reliable to manufacture.

The effect which the above hammer drill 1 can show | play is demonstrated.
In the hammer drill 1, a crank housing 22 that accommodates the crankshaft 20, a tool holder 4 to which a bit 6 is attached, a bevel gear 26 that rotates the tool holder 4, a sleeve member 40 that is disposed adjacent to the bevel gear 26, A barrel 60 disposed adjacent to the housing 22 is provided, and the sleeve member 40 is fixed in the axial direction of the tool holder 4 by being sandwiched between the crank housing 22 and the barrel 60.
Therefore, the sleeve member 40 can surely prevent the bevel gear 26 from moving back and forth, the bevel gear 26 or its peripheral members can be operated well, and the wear can be prevented to extend the life. Can do. Further, the bevel gear 26 and the like can be temporarily fixed in the crank housing 22 by the sleeve member 40, and accurate assembly of the crank housing 22 and the bevel gear 26 and the like is facilitated.

The sleeve member 40 has flanges 40f and 40g sandwiched between the crank housing 22 and the barrel 60, and the rear end portion of the sleeve member 40 is adjacent to the front side of the front portion 26a of the bevel gear 26. Even when the bevel gear 26 is disposed inside the front opening of the crank housing 22, the movement of the bevel gear 26 in the front-rear direction can be appropriately suppressed, and the flanges 40f and 40g have a shape that protrudes forward. Temporary fixing of the bevel gear 26 and the like can be performed appropriately.
Furthermore, since the sleeve member 40 is press-molded, the sleeve member 40 can be made to have higher hardness, and the sleeve member 40 itself can be prevented from being elastically deformed, so that the front-rear direction of the bevel gear 26 can be prevented. Can be appropriately suppressed.
In addition, the sleeve member 40 has a small protrusion 40h and a protrusion 40i, and the crank housing 22 is provided with a recess for receiving the small protrusion 40h and the protrusion 40i. It is possible to prevent a situation in which the bevel gear 26 and the spline ring 38 come into contact with the bevel gear 26 and rotate therewith, and an accurate operation can be ensured even if the sleeve member 40 is provided.

Further, a spline ring 38 that can be freely engaged with and disengaged from the bevel gear 26 is provided, and the outer diameter of the spline ring 38 is the same as the inner diameter of the sleeve member 40. The spline ring 38 for switching the operation can be operated even if the sleeve member 40 is provided, and the temporary assembly of the spline ring 38 and the bevel gear 26 can be performed more appropriately.
Furthermore, the groove 38b to the spline ring 38 is circumferentially in the groove 38b, the pawl 39a of the slide plate 39 for switching by moving back and forth the disengaging against bevel gear 26 splined ring 38, 39a are applied, the sleeve member 40 Since the cutout portion 40a that avoids the slide plate 39 is provided, even if the sleeve member 40 is provided, the engagement and disengagement of the spline ring 38 with respect to the bevel gear 26 by the slide plate 39 can be performed more smoothly. .

In addition, this invention is not limited to the said form, For example, the following changes can be given suitably.
Three or more receiving portions are provided in a state separated from each other. Omitting the relief part at the rear end of the cylinder, providing an escape part for the receiving part at the corner of the part (circlip) that can be received in the center of the cylinder, or providing a relief part in the cylinder part that can be received by both (all) receiving parts Or provide. A receiving part corresponding to the rear end of the cylinder is not provided, and instead a receiving part such as a circlip is installed in a state where it is separated in the front-rear direction. Various materials can be changed variously, and in particular, the material of the crank housing can be other than a magnesium alloy or a combination of a plurality of materials. The corners of the cylinder at the escape portion may be rounded, or the corners of the receiving portion may be filled with chamfered corners. As for the crank, a swash plate may be used in place of the crank projection and the rod that convert the rotational motion into the reciprocating motion.
The sleeve member, barrel, and crank housing are assembled into multiple parts, the sleeve member flange, notch, (small) protrusion, or one or more slide plate claws, or (small) protrusion Make the sleeve member longer (shorter) or the same size as each other, increase or decrease the number of teeth of the bevel gear or spline ring, make the rear part of the bevel gear the same size as the front part without reducing the diameter of the front part, The number and arrangement of various members, presence / absence of installation, and the like may be appropriately changed, such as forming by a method other than press molding. Moreover, the said form and the example of a change are applicable to another type hammer drill.

  1 .... hammer drill, 4. tool holder, 6. bit, 20. crankshaft (crank), 22. crank housing, 26 ... bevel gear, 38 ... spline ring (cam member), 38b ... groove , 39 .. Slide plate, 40 .. Sleeve member, 40 a .. Notch, 40 f, 40 g .. Flange, 40 h, 40 i .. (Small) protrusion, 60.

Claims (4)

A crank housing that houses the crank;
A tool holder for mounting a bit;
A bevel gear for rotating the tool holder;
A sleeve member disposed adjacent to the bevel gear;
A barrel disposed adjacent to the crank housing,
The sleeve member is fixed in the axial direction of the tool holder by being sandwiched between the crank housing and the barrel ,
Furthermore, it is provided with a cam member that is detachable from the bevel gear.
The outer diameter of the cam member is the same as the inner diameter of the sleeve member;
A groove is provided in the cam member,
A slide plate for switching engagement / disengagement of the cam member with respect to the bevel gear is hung on the groove,
The hammer drill according to claim 1, wherein the sleeve member is provided with a notch that avoids the slide plate . The sleeve member has a flange sandwiched between the crank housing and the barrel;
The hammer drill according to claim 1, wherein a rear end portion of the sleeve member is adjacent to a front side of the bevel gear. The hammer drill according to claim 1, wherein the sleeve member is press-molded. The sleeve member has a protrusion,
The hammer drill according to any one of claims 1 to 3, wherein the crank housing is provided with a recess for receiving the protrusion.

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