Rotary impact tool

Abstract

A rotary impact tool is provided. The rotary impact tool is configured to perform an impact operation and a rotation operation, wherein the impact operation is an operation of driving a tip tool in a direction of a driving axis, and the rotation operation is an operation of rotating the tip tool about the driving axis. The rotary impact tool has a tool holder that houses the tip tool in a detachable manner. The tool holder has a rotation transmission portion configured to transmit a rotation power to the tip tool. A coating film formed of a carbide of an element of Group 5 of the periodic table is formed on the rotation transmission portion. Accordingly, durability of the rotary impact tool that is capable of transmitting the rotation power to the tip tool can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a rotary impact tool. BACKGROUND

[0002] As a tool that applies an impact to a workpiece, a tool is described in Patent Literature 1, which has a cylinder that is provided inside a tool body, and a hammer portion that is housed in the cylinder in a manner so as to be movable inside the cylinder. In this tool, the hammer portion is made to reciprocate inside the cylinder and collide with an impact transmission member by performing pressurization of fluid into the cylinder and discharge of fluid from the cylinder, and accordingly an impact force is obtained.

[0003] [Related Art Literature]

[0004] [Patent Literature]

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2011-251388 SUMMARY

[0006] [Technical Problem to be Solved by the Invention]

[0007] In the technology described in Patent Literature 1, the prevention of breakage of the hammer portion is achieved by forming a coating film (thin film) on the surface of the hammer portion inside the cylinder. However, in recent years, in a rotary impact tool that is capable of not only transmitting an impact to a tip tool but also transmitting a rotational force to the tip tool, a technology that improves durability is required.

[0008] [Technical Solution to Solve the Technical Problem]

[0009] The present application can be implemented as follows.

[0010] According to one embodiment of the present application, a rotary impact tool that performs an impact operation and a rotational operation can be provided, wherein the impact operation is an operation of driving a tip tool along a driving axis, and the rotational operation is an operation of causing the tip tool to rotate around the driving axis. The rotary impact tool has a tool holder that houses the tip tool in a detachable manner. The tool holder has a rotational transmission portion that is configured to transmit a rotational force to the tip tool. A coating film formed of a carbide of a Group 5 element of the periodic table is formed on the rotational transmission portion.

[0011] [Effects of the Invention]

[0012] According to this embodiment, since the rotational transmission portion of the tool holder has the coating film formed of the carbide of the Group 5 element of the periodic table, wear of the rotational transmission portion due to transmission of the rotational force to the tip tool can be suppressed. Therefore, the durability of the tool holder can be improved, and thus the durability of the rotary impact tool can be improved. Attached Figure Description

[0013] Figure 1 It is a cross-sectional view of the hammer drill 1 with the top tool 18 installed.

[0014] Figure 2 This is a cross-sectional view used to illustrate the internal structure of the hammer drill 1.

[0015] Figure 3 This is a cross-sectional view of tool holder 60.

[0016] Figure 4 It means along Figure 1 Figure IV-IV shows the tool holder 60 and the top tool 18 for observation.

[0017] Figure 5 It is a cross-sectional view of a hammer drill 1A with a top tool 18A installed.

[0018] Figure 6 This is a sectional view used to illustrate the internal structure of the hammer drill 1A.

[0019] Figure 7 This is a cross-sectional view of tool holder 60A.

[0020] Figure 8 It means along Figure 5 Sectional views of tool holder 60A and top tool 18A observed in VIII-VIII.

[0021] [Explanation of reference numerals in the attached figures]

[0022] 1: hammer drill; 1A: hammer drill; 2: motor; 2A: motor; 3: drive mechanism; 3A: drive mechanism; 11: main body case; 11A: main body case; 13: handle; 13A: handle; 14: trigger; 18: tip tool; 18A: tip tool; 19: power cable; 20: motor main body portion; 25: motor shaft; 25A: motor shaft; 29: drive gear; 29A: drive gear; 30: motion conversion mechanism; 30A: motion conversion mechanism; 31: crankshaft; 32: connecting rod; 32A: intermediate shaft; 33: piston; 33A: rotating body; 34A: oscillating member; 35: cylinder; 35A: piston cylinder; 36: impact structure element; 36A: impact structure element; 40: rotation transmission mechanism; 40A: rotation transmission mechanism; 41: intermediate shaft; 46: sleeve; 60: tool holder; 60A: tool holder; 61: small diameter portion; 61A: small diameter portion; 62: large diameter portion; 62A: large diameter portion; 63: step portion; 63A: step portion; 71: anti-coming-off member; 95A: auxiliary handle; 111: motor housing portion; 111A: motor housing portion; 112: drive mechanism housing portion; 112A: drive mechanism housing portion; 131: gripping portion; 131A: gripping portion; 181: shank; 181A: shank; 182: circular arc groove; 182A: circular arc groove; 183: angular groove; 183A: angular groove; 311: driven gear; 311A: driven gear; 312: crank pin; 314: first gear; 361: ram; 361A: ram; 362: striker; 362A: striker; 365: air chamber; 365A: air chamber; 368: elastic member; 391: mode switching knob; 401A: first gear; 402A: second gear; 411: second gear; 412: small bevel gear; 413: large bevel gear; 461: pin; 601: barrel wall; 601A: barrel wall; 602: inner peripheral surface; 602A: inner peripheral surface; 603: long hole; 603A: long hole; 611: protrusion; 611A: protrusion; 613: first surface; 613A: first surface; 615: second surface; 615A: second surface; Al: drive axis; A2: rotation axis; A3: rotation axis; A4: central axis; A5: drive axis; A6: rotation axis; A7: central axis. DETAILED DESCRIPTION

[0023] Hereinafter, representative and non-limiting specific examples of the present application will be described in detail with reference to the accompanying drawings. This detailed description is merely intended to illustrate the preferred examples for carrying out the present application to those skilled in the art, and is not intended to limit the scope of the present application. In addition, the following disclosed additional features and disclosure can be used separately or together with other features or disclosure in order to provide further improved rotary impact tools, methods of manufacturing the same, and methods of using the same.

[0024] In addition, the combinations of features and processes disclosed in the following detailed description are not meant to be an exhaustive list of all possible implementations of the present application in its broadest sense. And, each feature of the representative examples described above and below, as well as in the independent and dependent claims, can be provided in combination with one another, when providing additional and useful implementations of the present application, without being limited to the examples as described herein or in the order as listed.

[0025] All features described in the present specification and / or claims are intended to be disclosed separately and independently from each other as being particular embodiments of the present application, and thus their disclosure as part of a particular embodiment of the present application is not to be construed in a manner that would limit the scope of the present application to only that particular embodiment. And, with respect to the disclosure of all numerical ranges and groups or sets, they are intended to disclose the intermediate structures as limitations of the disclosure of the present application at the time of filing the application and the claimed subject matter.

[0026] In one or more embodiments, the coating film can be a vanadium carbide (VC) coating film.

[0027] According to the above structure, since the vanadium carbide coating film is formed on the rotation transmission portion of the tool holder, the wear of the rotation transmission portion can be effectively suppressed. Therefore, the durability of the tool holder can be improved.

[0028] In one or more embodiments, the tool holder can be a forged member.

[0029] According to the above structure, the degree of freedom of the shape of the tool holder can be improved.

[0030] In one or more embodiments, the tool holder can have a cylindrical wall that can accommodate the tip tool. The rotation transmission portion can also be formed as a plurality of protrusions that protrude from the inner peripheral surface of the cylindrical wall to the radial inner side.

[0031] According to the above structure, by the plurality of protrusions that protrude from the inner peripheral surface of the cylindrical wall to the radial inner side, the rotational power can be transmitted to the tip tool, and the wear of the protrusions can be suppressed.

[0032] In one or more embodiments, the tool holder can have a cylindrical wall that can accommodate at least a portion of the impact member and the tip tool. The impact member can be configured to transmit an impact force to the tip tool by moving along the driving axis and colliding with the tip tool.

[0033] According to the above structure, the tool holder can exert the function of accommodating the impact member in addition to the function of accommodating the tip tool. Therefore, compared to the case where a member for accommodating the impact member is provided separately, the number of parts of the rotary impact tool can be reduced.

[0034] In one or more embodiments, the cylinder wall can be formed so as to be capable of housing at least a portion of the piston. The piston can be housed on the side of the driving axis of the impact member opposite the tip tool side. The piston can be configured to move the impact member along the driving axis.

[0035] According to the above structure, the tool holder can further function to house at least a portion of the piston. Thus, as compared with a case where a separate member for housing the piston is provided, the number of parts of the rotary impact tool can be reduced.

[0036] In one or more embodiments, the surface roughness of the inner circumferential surface of the portion of the cylinder wall for housing the impact member can be lower than the surface roughness of the surface of other portions of the cylinder wall.

[0037] According to the above structure, the air tightness between the impact member and the cylinder wall can be improved, and as compared with a case where the surface roughness of the other portions other than the housing portion is made as low as that of the housing portion, the tool holder can be easily manufactured.

[0038] In one or more embodiments, the tool holder can be formed of a steel material containing 0.04 wt% (0.04 mass percent) or more and 0.25 wt% (0.25 mass percent) or less of carbon.

[0039] According to the above structure, a tool holder suitable for transmitting rotary power to a tip tool can be provided.

[0040] In one or more embodiments, the rotary impact tool can have a motor for generating rotary power. The rotational axis of the motor can intersect the driving axis.

[0041] According to the above structure, a rotary impact tool in which the rotational axis of the motor is disposed so as to intersect the driving axis can be provided.

[0042] In one or more embodiments, the rotary impact tool can have a motor for generating rotary power. The rotational axis of the motor can be parallel to the driving axis.

[0043] According to the above structure, a rotary impact tool in which the rotational axis of the motor is disposed so as to be parallel to the driving axis can be provided.

[0044] <First Embodiment>

[0045] Reference Figures 1 to 4 A rotary impact tool according to the first embodiment will be described. Figure 1 and Figure 2A hammer drill 1 as an example of a rotary impact tool is shown. The hammer drill 1 is configured to be capable of an impact action and a rotary action. The impact action is an action of driving a tip tool 18 linearly along a driving axis line Al. The rotary action is an action of driving the tip tool 18 to rotate around the driving axis line Al. The driving axis line Al is also referred to as an impact axis line.

[0046] First, the outline structure of the hammer drill 1 will be described with reference to Figure 1 and Figure 2 The hammer drill 1 is mainly formed of a main body case 11 and a handle 13 connected to the main body case 11.

[0047] The main body case 11 has a driving mechanism housing portion 112 for housing the driving mechanism 3 and a motor housing portion 111 for housing the motor 2. The driving mechanism housing portion 112 is formed in a long strip shape extending in the driving axis line Al direction, and the motor housing portion 111 is disposed in a manner of protruding in a direction away from the driving axis line Al. Thus, the main body case 11 is formed in a substantially L shape as a whole. A tool holder 60 configured to be capable of attaching and detaching the tip tool 18 is provided at one end portion of the driving mechanism housing portion 112 in the driving axis line Al direction. In the present embodiment, a rotation axis line A2 of the motor shaft 25 extends in a direction orthogonal to the driving axis line Al.

[0048] Further, in the following description, for convenience of explanation, the extending direction of the driving axis line Al is defined as a front-rear direction of the hammer drill 1, in which the one end portion side provided with the tool holder 60 is defined as a front side of the hammer drill 1, and the opposite side thereof is defined as a rear side of the hammer drill 1. In addition, the extending direction of the rotation axis line A2 of the motor shaft 25 is defined as an up-down direction of the hammer drill 1, in which the side from which the motor housing portion 111 protrudes from the driving mechanism housing portion 112 is defined as a lower side, and the opposite side thereof is defined as an upper side.

[0049] Next, the detailed structure of each portion of the hammer drill 1 will be described.

[0050] The handle 13 is connected to the rear end portion of the main body case 11. The handle 13 has a grip portion 131 extending in a direction crossing the driving axis line Al. The handle 13 is formed in a substantially U shape as a whole. A trigger 14 configured to drive the motor 2 by a press operation is provided at a front portion of the grip portion 131.

[0051] As described above, the motor housing portion 111 of the main body case 11 houses the motor 2. As Figure 2As shown, the motor 2 includes a motor main body portion 20 including a stator and a rotor, and a motor shaft 25 provided extending from the rotor. In the present embodiment, as the motor 2, an alternating-current motor driven by receiving a power supply from an external power source via a power cable 19 is employed. Lower and upper end portions of the motor shaft 25 are rotatably supported by bearings held to the motor housing portion 111, respectively. A drive gear 29 is formed at the upper end portion of the motor shaft 25.

[0052] As described above, the drive mechanism housing portion 112 in the main body case 11 houses the drive mechanism 3. A front side portion of the drive mechanism housing portion 112 is formed in a substantially cylindrical shape along the drive axis Al. The tool holder 60 is housed in the front side portion of the drive mechanism housing portion 112. The tool holder 60 of the present embodiment has a hard coating, and thus is excellent in wear resistance. Details of the tool holder 60 are described later.

[0053] In the present embodiment, the drive mechanism 3 has a motion conversion mechanism 30, an impact structure element 36, and a rotation transmission mechanism 40.

[0054] The motion conversion mechanism 30 is configured to convert a rotational motion of the motor shaft 25 into a linear motion, and transmit the linear motion to the impact structure element 36. In the present embodiment, a crank mechanism is employed as the motion conversion mechanism 30. The motion conversion mechanism 30 has a crankshaft 31, a connecting rod 32, and a piston 33. The crankshaft 31 is disposed in parallel with the motor shaft 25 at a portion of the drive mechanism housing portion 112 that is located at a rear end portion and is located forward of the motor shaft 25. The crankshaft 31 has a driven gear 311 engaged with the drive gear 29 at a lower portion, and a crank pin 312 at an upper end portion. One end portion of the connecting rod 32 is rotatably connected to the crank pin 312. The other end portion of the connecting rod 32 is installed to the piston 33 via a pin. The piston 33 is slidably disposed within a cylindrical cylinder 35. When the motor 2 is driven, the piston 33 is reciprocated in the front-rear direction within the cylinder 35 along the drive axis Al. In the present embodiment, the cylinder 35 is housed within a sleeve 46. The sleeve 46 is supported to the main body case 11 so as to be rotatable about the drive axis Al with respect to the main body case 11. A rear end portion of the tool holder 60 is fitted to the sleeve 46.

[0055] The impact structure element 36 includes a hammer 361 and a striker 362. The hammer 361 is disposed on the front side of the piston 33 in a manner capable of sliding in the cylinder 35 in the front-rear direction along the driving axis Al. An air chamber 365 for moving the hammer 361 linearly by pressure variation of air generated by the reciprocating motion of the piston 33 is formed between the hammer 361 and the piston 33. The striker 362 is disposed on the front side of the hammer 361. The striker 362 is configured to transmit kinetic energy of the hammer 361 to the tip tool 18. In the present embodiment, the tool holder 60 is formed in a cylindrical shape, and the striker 362 is disposed on the inner side of the cylindrical wall 601 of the tool holder 60 in a slidable manner. An annular elastic member 368 (so-called O-ring) is sandwiched between the striker 362 and the tool holder 60. In the present embodiment, the elastic member 368 is fitted into an annular groove provided on the outer peripheral surface of the striker 362.

[0056] When the motor 2 is driven to move the piston 33 forward, the air in the air chamber 365 is compressed and the internal pressure rises. The hammer 361 is pushed out at high speed in the forward direction by the air spring and collides with the striker 362, thereby transmitting kinetic energy to the tip tool 18. Accordingly, the tip tool 18 is driven linearly along the driving axis Al, and the workpiece is impacted. On the other hand, when the piston 33 moves rearward, the air in the air chamber 365 expands and the internal pressure drops, and the hammer 361 is pulled into the rear. The hammer drill 1 performs an impact operation by causing the motion conversion mechanism 30 and the impact structure element 36 to repeatedly perform such operations.

[0057] The rotation transmission mechanism 40 is configured to transmit the torque of the motor shaft 25 to the tool holder 60. In the present embodiment, the rotation transmission mechanism 40 is configured as a reduction gear mechanism including a plurality of gears. The plurality of gears of the rotation transmission mechanism 40 include the driving gear 29, a driven gear 311, a first gear 314, a second gear 411, a small bevel gear 412, and a large bevel gear 413. The driven gear 311 and the first gear 314 are provided to the crankshaft 31. The second gear 411 and the small bevel gear 412 are provided to the intermediate shaft 41. The large bevel gear 413 is provided to the sleeve 46.

[0058] The intermediate shaft 41 is disposed in parallel with the motor shaft 25. In the present embodiment, the intermediate shaft 41 is disposed on the front side with respect to the motor shaft 25 and the crankshaft 31. The intermediate shaft 41 is supported by two bearings held to the driving mechanism housing portion 112 in a manner capable of rotating about a rotation axis A3 parallel to the rotation axis A2. The intermediate shaft 41 has the second gear 411 at the substantially central portion in the up-down direction and the small bevel gear 412 at the upper end portion. The second gear 411 is engaged with the first gear 314 provided to the lower side of the driven gear 311 on the crankshaft 31.

[0059] A large bevel gear 413 is disposed at the rear end of the sleeve 46 and meshes with a small bevel gear 412 at the upper end of the intermediate shaft 41. In the rotational transmission mechanism 40 of this embodiment, the rotational speeds of the motor shaft 25, intermediate shaft 41, crankshaft 31, and sleeve 46 (tool holder 60) decrease sequentially through these reduction gear mechanisms.

[0060] The hammer drill 1 in this embodiment is configured such that either a hammer drill mode or a hammer impact mode can be selected via an operation mode switching knob 391. The hammer drill mode is a mode that performs impact and rotational actions by driving the motion conversion mechanism 30 and the rotation transmission mechanism 40. The hammer impact mode is a mode that performs only impact actions by driving only the motion conversion mechanism.

[0061] The tool holder 60 will now be described in detail. First, the tip tool 18 mounted on the tool holder 60 will be described. The tip tool 18 is also referred to as a bit. The tip tool 18 has a shank 181 (see reference 181) that is mounted on the tip tool holder 60. Figure 1 ).exist Figure 4 In the cross-sectional view shown, the shank 181 has an arcuate groove 182 and a corner groove 183 recessed toward the central axis A4 of the tip tool 18. The arcuate groove 182 and the corner groove 183 extend in a straight line along the central axis A4. In this embodiment, the tip tool 18 has two arcuate grooves 182 symmetrical with respect to the central axis A4 and three corner grooves 183 arranged at predetermined intervals in the circumferential direction around the central axis A4. Furthermore, when the tip tool 18 is mounted on the tool holder 60, the central axis A4 of the tip tool 18 is substantially aligned with the drive axis A1.

[0062] As described above, the tool holder 60 is housed in the front portion of the drive mechanism receiving section 112. Figure 3 and Figure 4 As shown, the tool holder 60 is a cylindrical component extending along the drive axis A1. A tipped tool 18 is housed inside the cylindrical wall 601 of the tool holder 60. Specifically, the shank 181 of the tipped tool 18 is inserted into the inner side of the cylindrical wall 601 from the front.

[0063] In this embodiment, the cylindrical wall 601 of the tool holder 60 has: a small-diameter portion 61, which is provided on the front side in the direction of the drive axis A1; a large-diameter portion 62, which is provided on the rear side in the direction of the drive axis A1; and a stepped portion 63, which connects the small-diameter portion 61 and the large-diameter portion 62. The inner and outer diameters of the large-diameter portion 62 are respectively formed to be larger than the inner and outer diameters of the small-diameter portion 61. The radial thickness of the cylindrical wall 601 of the tool holder 60 is approximately equal in the front-rear direction. The large-diameter portion 62 is fitted into the front portion of the sleeve 46 and is fixed to the sleeve 46 by a pin 461 (see reference).Figure 2 ). Thus, the tool holder 60 is able to rotate together with the sleeve 46 with respect to the main body case 11 about the drive axis Al. The impact structure element 36 (the striker 362) is housed in the front portion of the sleeve 46 (the cylinder 35) and the large diameter portion 62, and slides in the front-rear direction within the large diameter portion 62.

[0064] Two long holes 603 are provided on the tool holder 60, which extend linearly in the direction of the drive axis Al through the cylinder wall 601 in the radial direction. The long holes 603 are symmetrically arranged with respect to the drive axis Al. In the present embodiment, the long holes 603 are provided in the rear portion of the small diameter portion 61. A dropout preventing member 71 (refer to FIG. 6) for restricting the dropout of the tip tool 18 inserted in the tool holder 60 or allowing the dropout of the tip tool 18 from the tool holder 60 is arranged on the long holes 603. The dropout preventing member 71 is able to move in the direction of the drive axis Al within the long holes 603. Although detailed description is omitted, a force applying mechanism is provided around the tool holder 60, which applies a force to the dropout preventing member 71 in the direction of the drive axis Al. The force applying mechanism restricts the dropout of the tip tool 18 from the tool holder 60 (the inside of the cylinder wall 601). Figure 1 and Figure 2 ). Although detailed description is omitted, a force applying mechanism is provided around the tool holder 60, which applies a force to the dropout preventing member 71 in the direction of the drive axis Al. The force applying mechanism restricts the dropout of the tip tool 18 from the tool holder 60 (the inside of the cylinder wall 601).

[0065] A plurality of protrusions 611 are provided at predetermined positions in the circumferential direction of the rear portion of the small diameter portion 61. The protrusions 611 are portions protruding from the inner circumferential surface 602 of the cylinder wall 601 to the radial direction inner side. The protrusions 611 extend linearly in the direction of the drive axis Al. The protrusions 611 are arranged to correspond to the positions of the three corner grooves 183 in the circumferential direction. The protrusions 611 have a first surface 613 in the circumferential direction about the drive axis Al and a second surface 615 intersecting the circumferential direction.

[0066] When the user inserts the tip tool 18 into the tool holder 60 and positions the protrusion 611 of the tool holder 60 so as to be fitted into the corner groove 183 of the tip tool 18, the escape preventing member 71 is pressed by the rear end portion of the shank 181 while moving to the radially outer side, and is engaged with the circular-arc groove 182 of the shank 181 via the long hole 603 of the tool holder 60. The rotational power of the motor 2 is transmitted to the sleeve 46 and the tool holder 60 through the rotational transmission mechanism 40, and when the sleeve 46 and the tool holder 60 rotate around the driving axis line Al, the protrusion 611 abuts against the corner groove 183 of the tip tool 18 to transmit the rotational power of the motor 2 to the tip tool 18. More specifically, the second surface 615 in the protrusion 611 abuts against the side surface of the corner groove 183 of the tip tool 18 to transmit the rotational power of the motor 2 to the tip tool 18. The protrusion 611 functions as a rotational transmission portion for transmitting the rotational power of the motor 2 to the tip tool 18. The second surface 615 is also a torque transmission site (torque transmission surface) for transmitting the torque to the tip tool 18.

[0067] Next, the material of the tool holder 60 and the coating film formed on the tool holder 60 will be described. The tool holder 60 is formed of a material containing carbon and having iron as a main component (steel material). The tool holder 60 is formed by forging the steel material. In the present embodiment, the carbon content is 0.04 wt% or more (hereinafter, abbreviated as % (percent)). In addition, in the present embodiment, the carbon content is 0.25% or less. As an example of the material of the tool holder 60, a mechanical structural carbon steel (for example, S10C, S15C, S17C), a chromium-molybdenum steel (for example, SCM415), or the like can be given.

[0068] A hard coating film is formed on the surface of the tool holder 60. The hard coating film is formed of a carbide of a Group 5 element in the periodic table. The Group 5 element is, for example, vanadium (V), niobium (Nb), Ta (tantalum), and Db In the present embodiment, a vanadium carbide (VC) coating film is formed on the surface of the tool holder 60 as the hard coating film.

[0069] The hard coating film can be formed by subjecting an intermediate product of the tool holder 60, which is obtained by forging the above-described steel material into the shape of the tool holder 60, to a surface hardening treatment. As the surface hardening treatment, for example, TD treatment can be cited. TD treatment (Toyota Diffusion Coating Process) is a treatment in which a treated material is immersed and held in a molten salt bath at around 850°C to 1050°C, thereby forming a carbide layer on the surface of the treated material. The molten salt contains boric acid (borate, borax) as a main material and a target element for forming carbide. By TD treatment, for example, an extremely hard coating film having a hardness (Hv) of around 2000 to 3800 is formed.

[0070] Further, the tool holder 60 of the embodiment is formed such that the surface roughness of the inner peripheral surface 602 of the large-diameter portion 62 is smaller than the surface roughness of the surfaces of other portions. In the embodiment, the tool holder 60 is formed by grinding the inner peripheral surface 602 of the large-diameter portion 62 of the intermediate product subjected to TD treatment.

[0071] The hammer drill 1 of the first embodiment described above includes the tool holder 60 having a vanadium carbide coating film. Therefore, since the wear of the protrusion 611 for transmitting rotation to the corner pocket 183 of the tip tool 18 can be suppressed, the durability of the tool holder 60 and the hammer drill 1 can be improved.

[0072] Further, the tool holder 60 houses the striker 362 as an impact member for impacting the tip tool 18 in a slidable manner in addition to the tip tool 18. Therefore, compared with a structure in which a member housing the striker 362 is provided separately, the number of components of the hammer drill 1 can be reduced.

[0073] Since the tool holder 60 is a forged member, the degree of freedom of shape can be improved. Further, since the tool holder 60 is formed of a steel material containing 0.04% or more and 0.25% or less of carbon, it is also suitable as a forged member. Moreover, the tool holder 60 has a hard coating film formed by subjecting a forged member formed of a steel material containing 0.04% or more and 0.25% or less of carbon to TD treatment using a Group 5 element of the periodic table. Therefore, a hammer drill 1 having a tool holder 60 capable of withstanding load at the time of work and wear resistance can be provided.

[0074] Further, according to the embodiment, a hammer drill 1 having improved durability of the tool holder 60 and the hammer drill 1 and a rotational axis A2 of the motor 2 disposed in a manner intersecting the drive axis Al can be provided.

[0075] Further, in the tool holder 60, the surface roughness of the inner peripheral surface 602 of the large diameter portion 62 is formed to be smaller than the surface roughness of other portions. Thus, the air tightness between the inner peripheral surface 602 of the cylindrical wall 601 in the large diameter portion 62 of the tool holder 60 and the striker 362 can be maintained by the elastic member 368.

[0076] Further, the surface roughness of the outer peripheral surface of the large diameter portion 62 can also be formed to be smaller than the surface roughness of other portions of the tool holder 60 except for the inner peripheral surface 602 of the large diameter portion 62. Thus, the tool holder 60 can be fitted to the sleeve 46 with high precision. Further, the assembly precision of the sleeve 46 and the tool holder 60 can be ensured.

[0077] <Second Embodiment>

[0078] Hereinafter, the hammer drill 1A as a rotary impact tool according to the second embodiment will be described with reference to the drawings. Figures 5 to 8 The hammer drill 1A is configured to perform an operation (impact operation) of reciprocating the tip tool 18A along the drive axis (impact axis) A5 in a straight line and an operation (rotation operation) of rotating the tip tool 18A about the drive axis A5, like the hammer drill 1 of the first embodiment. The hammer drill 1A is configured to perform the impact operation and the rotation operation by the same mechanism as the hammer drill 1 of the first embodiment.

[0079] The outer contour of the hammer drill 1A is mainly formed by the main housing 11A and the handle 13A. As shown in FIG. 1A, the main housing 11A is formed in an elongated shape and extends along the drive axis A5. The main housing 11A is formed in a cylindrical shape in the outer peripheral surface thereof. Figure 5 As shown in FIG. 1A, the main housing 11A is formed in a cylindrical shape in the outer peripheral surface thereof. The main housing 11A is formed in a cylindrical shape in the outer peripheral surface thereof. Figure 6 As shown in FIG. 1A, the main housing 11A is formed in a cylindrical shape in the outer peripheral surface thereof. The main housing 11A is formed in a cylindrical shape in the outer peripheral surface thereof. The handle 13A includes a grip portion 131A to be gripped by a user. The grip portion 131A extends in a direction (more specifically, a substantially orthogonal direction) intersecting the drive axis A5 and projects from the main housing 11A in a direction away from the drive axis A5 in a cantilevered manner.

[0080] Furthermore, in the following description, the direction of extension of the drive axis A5 is defined as the front-rear direction of the hammer drill 1A, with the end portion side on which the tool holder 60A is provided being defined as the front side of the hammer drill 1A, and the opposite side being defined as the rear side of the hammer drill 1A. Also, the direction orthogonal to the drive axis A5 and corresponding to the direction of extension of the grip portion 131A is defined as the up-down direction, with the proximal end portion side of the grip portion 131A being defined as the upper side, and the distal end side of the grip portion 131A being defined as the lower side. A power supply cable 19 for supplying power to the motor 2A from an external power source is disposed on the lower side of the grip portion 131A. A trigger 14 configured to drive the motor 2 by a press operation is provided on the front portion of the grip portion 131A.

[0081] The main body case 11A includes a motor housing portion 111A and a drive mechanism housing portion 112A.

[0082] As shown in Figure 5 and Figure 6 , the motor housing portion 111A houses the motor 2A. The motor 2A includes a motor main body portion 20 including a stator and a rotor, and a motor shaft 25A extending from the rotor. In the present embodiment, the rotational axis A6 of the motor shaft 25A is disposed in parallel with the drive axis A5 and extends in the front-rear direction. The front end portion and the rear end portion of the motor shaft 25A are each rotatably supported by a bearing held to the motor housing portion 111A. A drive gear 29A is formed on the front end portion of the motor shaft 25A.

[0083] The drive mechanism housing portion 112A is formed as an elongated cylindrical body extending in the front-rear direction along the drive axis A5, and houses the drive mechanism 3A. The front side portion of the drive mechanism housing portion 112A is used to house the cylindrical tool holder 60A. The tool holder 60A is supported to the main body case 11A in a manner so as to be rotatable about the drive axis A5 with respect to the main body case 11A. The tool holder 60A has a hard coating similarly to the tool holder 60 of the first embodiment, and is excellent in wear resistance. Details of the tool holder 60A are described later.

[0084] The drive mechanism 3A has a motion conversion mechanism 30A, an impact structure element 36A, and a rotation transmission mechanism 40A.

[0085] The motion conversion mechanism 30A is configured to convert the rotational motion of the motor shaft 25A to linear motion and transmit it to the impact structure element 36A. In the present embodiment, as Figure 6As shown, the motion conversion mechanism 30A has an intermediate shaft 32A, a rotating body 33A, a swing member 34A, and a piston cylinder 35A. The intermediate shaft 32A is arranged to extend in the front-rear direction in parallel with the motor shaft 25A. The front end and the rear end of the intermediate shaft 32A are rotatably supported by two bearings held to the main body case 11A. The rotating body 33A is mounted to the outer peripheral portion of the intermediate shaft 32A and can rotate integrally with the intermediate shaft 32A. The swing member 34A is mounted to the outer peripheral portion of the rotating body 33A and swings in the front-rear direction as the rotating body 33A rotates. The piston cylinder 35A is formed in a bottomed cylindrical shape and is held to the tool holder 60A so as to be slidable in the front-rear direction. The piston cylinder 35A reciprocates in the front-rear direction as the swing member 34A swings.

[0086] As with the first embodiment, the impact structure 36A includes a hammer 361A and a striker 362A. In the present embodiment, the impact structure 36A is housed in the tool holder 60A. The hammer 361A is arranged in the piston cylinder 35A housed in the tool holder 60A so as to be slidable in the front-rear direction. An air chamber 365A for linearly moving the hammer 361A is formed between the hammer 361A and the piston cylinder 35A. The striker 362A is configured to transmit kinetic energy of the hammer 361A to the tip tool 18A.

[0087] As with the first embodiment, when the motor 2A is driven and the piston cylinder 35A moves in the front direction, the air in the air chamber 365A is compressed and the internal pressure rises. In the present embodiment, the piston cylinder 35A also functions as a so-called piston. The hammer 361A is pushed out in the front direction at high speed by the action of the air spring and collides with the striker 362A, transmitting kinetic energy to the tip tool 18A. Accordingly, the tip tool 18A is linearly driven along the drive axis A5 and impacts the workpiece. On the other hand, when the piston cylinder 35A moves in the rear direction, the air in the air chamber 365A expands and the internal pressure drops, thereby pulling the hammer 361A in the rear direction. The hammer drill 1A performs an impact action by causing the motion conversion mechanism 30A and the impact structure 36A to repeatedly perform such actions.

[0088] The rotational transmission mechanism 40A is configured to transmit the torque of the motor shaft 25A to the tool holder 60A. Similar to the first embodiment, the rotational transmission mechanism 40A is configured as a reduction gear mechanism comprising multiple gears. These gears include a drive gear 29A, a driven gear 311A, a first gear 401A, and a second gear 402A. The drive gear 29A is located at the front end of the motor shaft 25A. The driven gear 311A ​​is located at the rear end of the intermediate shaft 32A and meshes with the drive gear 29A. The first gear 401A is located at the front end of the intermediate shaft 32A. The second gear 402A is located on the outer periphery of the tool holder 60A and meshes with the first gear 401A. In this embodiment, the rotational speed decreases sequentially through the reduction gear mechanism, in the order of motor shaft 25A, intermediate shaft 32A, and tool holder 60A.

[0089] The hammer drill 1A in this embodiment is configured to select one of three operating modes: drilling mode, hammering mode as described in the first embodiment, and hammer drilling mode. The drilling mode is an operating mode in which the power transmission in the motion conversion mechanism 30A is cut off and only the rotary transmission mechanism 40A is driven, thereby performing only the drilling action.

[0090] The tool holder 60A will now be described in detail. First, the top tool 18A, which is mounted on the tool holder 60A, will be described. Figure 8 In the cross-sectional view shown, an arcuate groove 182A and a corner groove 183A recessed toward the central axis A7 of the tip tool 18A are provided on the shank 181A. The arcuate groove 182A and the corner groove 183A extend in a straight line along the central axis A7. In this embodiment, the tip tool 18A has two arcuate grooves 182A, which are symmetrical with respect to the central axis A7; and two corner grooves 183A, which are provided at predetermined intervals in the circumferential direction around the central axis A7. In addition, when the tip tool 18A is mounted on the tool holder 60A, the central axis A7 of the tip tool 18A is substantially aligned with the drive axis A5.

[0091] The tool holder 60A is a cylindrical component extending along the drive axis A5. The cylindrical wall 601A of the tool holder 60A has: a small-diameter portion 61A, located at the front in the direction of the drive axis A5; a large-diameter portion 62A, located at the rear in the direction of the drive axis A5; and a multi-stepped portion 63A connecting the small-diameter portion 61A and the large-diameter portion 62A. The inner and outer diameters of the large-diameter portion 62A are respectively larger than the inner and outer diameters of the small-diameter portion 61A. The outer periphery of the tool holder 60A is supported by bearings held in the main body housing 11A in a manner that allows it to rotate relative to the main body housing 11A about the drive axis A5. In addition to the tip tool 18A, the tool holder 60A also houses an impact structure element 36A and a piston cylinder 35A.

[0092] As with the first embodiment, two long holes 603A are provided on the tool holder 60A, which pass through the cylindrical wall 601A in the radial direction and extend linearly in the direction of the drive axis A5. In addition, a dropout preventing member 71 (refer to Figure 5 and Figure 6 ) is disposed in the long hole 603A. In addition, a protruding portion 611A protruding from the inner peripheral surface 602A of the cylindrical wall 601A to the radial inner side is provided in the small-diameter portion 61A. The protruding portion 611A extends linearly in the direction of the drive axis A5. The protruding portion 611A is disposed so as to correspond to the positions of the two corner grooves 183A in the circumferential direction. The protruding portion 611A has a first surface 613A along the circumferential direction around the drive axis A5 and a second surface 615A intersecting the circumferential direction. The mounting method of the tip tool 18A to the tool holder 60A is the same as that of the first embodiment, and thus the description is omitted.

[0093] As with the first embodiment, when the tool holder 60A is rotated by transmitting the rotational power of the motor 2A to the tool holder 60A through the rotation transmission mechanism 40A, the protruding portion 611A abuts against the side surface of the corner groove 183A to transmit the rotational power of the motor 2A to the tip tool 18A. In more detail, the second surface 615A in the protruding portion 611A abuts against the corner groove 183A of the tip tool 18A, thereby transmitting the rotational power of the motor 2A to the tip tool 18A. The protruding portion 611A functions as a rotation transmission portion for transmitting the rotational power of the motor 2A to the tip tool 18A. The second surface 615A is also a torque transmission site (torque transmission surface) that transmits torque to the tip tool 18A.

[0094] The material of the tool holder 60A and the coating film formed on the tool holder 60A are the same as those of the first embodiment. That is, the tool holder 60A is formed by forging a material (steel material) containing carbon and having iron as the main component. In addition, the coating film is formed of an element belonging to Group 5 of the periodic table. The coating film can be formed by TD processing. Furthermore, in the present embodiment, the surface roughness of the inner peripheral surface 602A of the large-diameter portion 62A of the tool holder 60A is substantially equal to the surface roughness of the surface of the other portions.

[0095] According to the second embodiment described above, as with the first embodiment, it is possible to provide a hammer drill 1A in which the durability of the tool holder 60A and the hammer drill 1A is improved and the rotational axis A6 of the motor 2A is disposed in parallel to the drive axis A5.

[0096] In addition, the tool holder 60A is formed so as to be capable of accommodating the piston cylinder 35A in addition to the tip tool 18A. Therefore, the tool holder 60A can be made to function in multiple ways, including the function of accommodating the tip tool 18A and transmitting rotational power and the function of accommodating the piston cylinder 35A. In addition, as compared with a structure in which a separate member for accommodating the piston cylinder 35A is provided, the number of components of the hammer drill 1A can be reduced.

[0097] <Correspondence>

[0098] The correspondence between each structural element of the above-described embodiment and each structural element of the technology according to the present application is shown below. However, each structural element of the embodiment is merely an example and does not limit each structural element of the technology according to the present application.

[0099] The hammer drills 1, 1A are examples of "rotary impact tools". The tip tools 18, 18A are examples of "tip tools". The drive axes Al, A5 are examples of "drive axes". The tool holders 60, 60A are examples of "tool holders". The protrusions 611, 611A, the second surfaces 615, 615A are examples of "rotation transmission portions". The cylinder walls 601, 601A are examples of "cylinder walls". The protrusions 611, 611A are examples of "protrusions". The plungers 362, 362A are examples of "impact members". The piston cylinder 35A is an example of a "piston". The large-diameter portion 62 is an example of a "portion for accommodating an impact member". The inner circumferential surfaces 602, 602A are examples of "inner circumferential surfaces". The motors 2, 2A are examples of "motors". The rotation axes A2, A6 are examples of "rotation axes".

[0100] <Other Embodiments>

[0101] The tool holders 60, 60A can also not be forged members, but can be cast members, for example.

[0102] The coating film of the tool holder 60, 60A is not limited to a carbide of an element belonging to Group 5 of the periodic table, but can be formed of a carbide of chromium (Cr). The chromium carbide coating film can be formed by TD processing. According to this method, the durability of the tool holder 60, 60A can also be improved in the same manner as in the above-described embodiment.

[0103] In the first embodiment, the surface roughness of the inner circumferential surface 602 of the portion for accommodating the plunger 362 (the large-diameter portion 62) can be the same as the surface roughness of the surfaces of other portions.

[0104] The coating film can also be formed without the TD treatment. For example, the coating film can also be formed by PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition).

[0105] The coating film can also not be formed on the entire tool holder 60, 60A, but only on a portion for transmitting rotation to the tip tool 18, 18A. For example, the coating film can be formed only on the protruding portions 611, 611A, or only on the second surfaces 615, 615A in the protruding portions 611, 611A.

[0106] The configuration of the rotational axis A2, A6 of the motor 2, 2A with respect to the driving axis Al, A5 of the tool holder 60, 60A can also be other than parallel or orthogonal. The rotational axis A2, A6 of the motor 2, 2A can also intersect the driving axis Al, A5 at a prescribed angle.

[0107] The present application is not limited to the above-described embodiments, and can be implemented by various structures within a range not departing from the gist of the present application. For example, in order to solve part or all of the above-described technical problems, or in order to achieve part or all of the above-described technical effects, the technical features in the embodiments corresponding to the technical features in each of the modes described in the summary of the application can be appropriately replaced or combined. In addition, if the technical features are not described as essential in the specification, they can be appropriately deleted.

Claims

1. A rotary impact tool that performs impact and rotation actions, wherein, The impact action is the movement of driving the tip tool along the drive axis, and the rotation action is the movement of rotating the tip tool around the drive axis. Its features are, The rotary impact tool has a tool holder that detachably houses the tip tool, and the tool holder also has a rotation transmission part configured to transmit rotational power to the tip tool. A coating made of carbides of Group 5 elements from the periodic table is formed on the rotary transmission section. The tool holder has a cylindrical wall capable of accommodating at least a portion of the tip tool and the impact member, the impact member being configured to transmit impact force to the tip tool by moving along the drive axis and colliding with the tip tool. The surface roughness of the inner circumferential surface of the portion of the cylinder wall used to house the impact member is lower than the surface roughness of other portions of the cylinder wall.

2. The rotary impact tool according to claim 1, characterized in that, The coating is a vanadium carbide (VC) coating.

3. The rotary impact tool according to claim 1 or 2, characterized in that, The tool holder is a forging.

4. The rotary impact tool according to claim 1 or 2, characterized in that, The tool holder has a cylindrical wall capable of accommodating the tip tool. The rotation transmission part is formed as a plurality of protrusions that protrude radially inward from the inner circumference of the cylinder wall.

5. The rotary impact tool according to claim 1 or 2, characterized in that, The cylinder wall is formed to accommodate at least a portion of a piston on the side opposite to the top tool side on the drive axis, the piston being configured to move the impact member along the drive axis.

6. The rotary impact tool according to claim 1 or 2, characterized in that, The tool holder is made of steel containing 0.04 wt% to 0.25 wt% carbon.

7. The rotary impact tool according to claim 1 or 2, characterized in that, The rotary impact tool has a motor for generating the rotary power, and the rotation axis of the motor intersects the drive axis.

8. The rotary impact tool according to claim 1 or 2, characterized in that, The rotary impact tool has a motor for generating the rotary power, and the rotation axis of the motor is parallel to the drive axis.

Images