JP6026861B2 - Impact tool - Google Patents

Description

  The present invention relates to an impact tool for performing a hammering operation on a workpiece.

As shown in Patent Document 1 below, an electric hammer including a striker for hammering a hammer bit and a cylinder for housing a piston is known.
The cylinder in such an electric hammer is inserted from the front into a cylindrical cylinder holding portion formed in the front region of the gear housing, and its insertion end abuts against an end surface in a direction intersecting the insertion direction. Thus, the rear end position is fixed and fixed (see, for example, [0016] in FIG. 5 and FIG. 5).

JP 2008-279588 A

In the electric hammer, only the rear portion of the cylinder is supported by the gear housing, and in particular, there is only one insertion end portion in the direction intersecting the hammer operation direction.
Therefore, the stress and reaction force of hammer operation transmitted to the cylinder is applied only to the thin rear end face of the cylinder or the end face of the cylinder holding part, and the load is concentrated on one place, which requires design considerations. However, there is a limit to the improvement in rigidity and durability related to the fixing of the cylinder.
Therefore, the main object of the present invention is to provide an impact tool that can fix a cylinder in a state of high rigidity and durability.

In order to achieve the above object, the invention described in claim 1 includes a crank housing that houses a crank and a cylinder that is housed in the crank housing, and is pushed rearward at a plurality of front and rear positions of the crank housing. A receiving portion for receiving the cylinder is provided, and at least one portion of the cylinder received by the receiving portion is a metal circlip .
According to a second aspect of the present invention, in the above invention, at least one of the receiving portions is arranged to receive a rear side of a rear end portion of the cylinder.
According to a third aspect of the present invention, in the above invention, the crank housing is made of a magnesium alloy.
According to a fourth aspect of the present invention, in the above invention, the corner portion of the receiving portion is rounded, and the corner portion of the cylinder corresponding to the corner portion of the receiving portion escapes from the corner portion of the receiving portion. It has the part.

According to the first aspect of the present invention, a receiving portion for receiving a cylinder pushed rearward is provided at a plurality of front and rear positions of the crank housing, and at least one portion of the cylinder received by the receiving portion is a metal circlip der Runode, cylinder can be reliably receive the receive burden to reduce the unit, can be improved to extend the life of the equal additional durability to prevent cracking, without circlip is flexes recklessly, Ru can let securely received in the receiving portion of the circlip, an effect that.
Further, according to the invention described in claim 2, in the above invention, since it is arranged to receive the rear side of the rear end portion of the cylinder, in addition to the above effects, the entire cylinder can be subjected to a backward force. There exists an effect that a receiving part can be arranged.
In addition , according to the invention of claim 3 , in the above invention, since the crank housing is made of a magnesium alloy, in addition to the above effects, the crank housing in which the cylinder is housed can be made lightweight while being rigid, There is an effect that the cylinder can be received more reliably.
According to a fourth aspect of the present invention, in the above invention, the corner portion of the receiving portion is rounded, and the corner portion of the cylinder corresponding to the corner portion of the receiving portion is an angle of the receiving portion. In addition to the above effects, stress concentration at the corners is avoided and the cylinder is more securely received, further improving the durability and extending the life of the receiving part. There is an effect that it can be realized.

(A) is a center longitudinal cross-sectional view of the hammer drill which concerns on this invention, (b) is a figure of the front-end | tip part of (a) at the time of the largest retraction | saving of a bit. It is an enlarged view of the receiving part A periphery in FIG.

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

Fig.1 (a) is a longitudinal cross-sectional view of the hammer drill 1 which is an example of an impact tool.
The hammer drill 1 includes 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 (left side in FIG. It has a hand grip 8 which is formed on the rear side of the main body housing 2 and is gripped by an operator.
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. In more detail, as shown in FIG. 2, 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.
A spline ring 38 is attached to the front side of the bevel gear 26 so as to be able to move back and forth on the outer wall of the tool holder 4 and to rotate together with the tool holder 4 at any front and back position within the moving range. The spline ring 38 is connected to a slide plate 39 extending in the front-rear direction. In the state where the slide plate 39 is on the front side (the state shown in FIG. 1A), the spline ring 38 is separated from the bevel gear 26 and the motor 10 or the intermediate shaft unit. The rotation of the bevel gear 26 by 25 is not transmitted to the spline 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 backward from the state shown in FIG. 1A by an operation unit (not shown). At this time, the driving force of the motor 10 is intermediate. The tool holder 4 is reached via the shaft unit 25, the bevel gear 26 and the spline ring 38.

Further, on the rear side of the head portion of the impact bolt 37, a ring 40 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.

A metal circlip 58 (a circumferential member provided around the cylinder 32 body) fixed in the same manner as the circlip 48 is provided behind the ring 56.
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.

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. The maximum pressing state of the bit 6 is shown in FIG.
When the bit 6 is pushed backward, the small spring 46 and the spring 54 are further compressed via the impact bolt 37, the ring 40 , 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.

  Even if the pressing force, impact 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.

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 and cylinders 32 that are accommodated in the crank housing 22 are provided, and receiving portions A that receive the cylinders 32 that are pushed backward at a plurality of front and rear positions of the crank housing 22. B is provided. Therefore, compared to the case where only the rear surface (the rear end thick portion) of the cylinder 32 is received, the cylinder 32 pushed rearward by striking or the like can be received more reliably, and the burden on the receiving portion is reduced by dispersion, and cracks are generated. The durability can be further improved or the life can be extended, for example, by preventing the occurrence. Further, at least one of the receiving portions (here, receiving portion B) can be arranged relatively freely in the crank housing 22, and like the receiving portion B, it is arranged in a relatively high rigidity portion such as the upper and lower walls of the front cylindrical portion. If so, it is possible to perform a more reliable reception.

Moreover, since the receiving part A is arrange | positioned so that the rear end part rear side of the cylinder 32 may be received, the receiving part A which can receive the cylinder 32 whole about the effect | action to back can be provided.
Furthermore, since the part in the cylinder 32 received by the receiving part B is a metal circlip 58 (circumferential member), the cylinder 32 (circlip 58) does not bend in the dark without receiving in the receiving part B. It can be received firmly.
Furthermore, since the crank housing 22 is made of a magnesium alloy, the crank housing 22 can be increased in rigidity while being lightweight, and the cylinder 32 can be received more reliably.
In addition, the corner portion of the receiving portion A is rounded, and the corner portion of the cylinder 32 corresponding to the corner portion of the receiving portion A has a relief portion E that escapes from the corner portion of the receiving portion A. Concentration of stress in the portion can be avoided, the cylinder 32 can be more securely received, and the durability of the receiving portion A can be further improved and the life can be extended.

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 number and arrangement of various members and the presence / absence of installation may be changed as appropriate. Moreover, the said form and the example of a change are applicable to other impact tools, such as an electric hammer.

  1 ··· hammer drill (blow tool), 20 · · crankshaft (crank), 22 · · crank housing, 32 · · cylinder, 58 · · circlip (peripheral member, part of the cylinder), A, B · · · Receiving part, E ... escape part.

Claims (4)

A crank housing that houses the crank;
A cylinder housed in the crank housing;
Receiving portions for receiving the cylinder pushed backward are provided at a plurality of front and rear positions of the crank housing ,
The striking tool, wherein at least one portion of the cylinder received by the receiving portion is a metal circlip . The striking tool according to claim 1, wherein at least one of the receiving portions is arranged to receive a rear side of a rear end portion of the cylinder. The crank housing, impact tool as defined in claim 1 or claim 2, characterized in that it is made of magnesium alloy. The corner of the receiving part is rounded,
The striking portion according to any one of claims 1 to 3 , wherein a corner portion of the cylinder corresponding to a corner portion of the receiving portion has an escape portion that escapes from the corner portion of the receiving portion. tool.

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