Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D17/08—Means for retaining and guiding the tool bit, e.g. chucks allowing axial oscillation of the tool bit
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D17/06—Hammer pistons; Anvils ; Guide-sleeves for pistons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D17/24—Damping the reaction force
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2217/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D2217/0011—Details of anvils, guide-sleeves or pistons
  • B25D2217/0019—Guide-sleeves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
  • B25D2250/245—Spatial arrangement of components of the tool relative to each other

Definitions

• the invention relates to an impact tool having an improved layout structure.
• Impact tools such as impact chisels, hammers, impact drills, or the like
• Typical impact tools generally have a motor, such as an electric, pneumatic or hydraulic motor, a piston which is driven by the motor to slide reciprocately in a cylinder, a striker which is disposed in the cylinder so as to be driven by the piston to follow the reciprocating movement of the cylinder, and a tool bit, such as a chisel bit, a drill bit, or the like, which is impacted by the striker to move forwardly and is guided at least partly by means of the same cylinder.
• a motor such as an electric, pneumatic or hydraulic motor
• a piston which is driven by the motor to slide reciprocately in a cylinder
• a striker which is disposed in the cylinder so as to be driven by the piston to follow the reciprocating movement of the cylinder
• a tool bit such as a chisel bit, a drill bit, or the like, which is impacted by the striker to move forwardly and
• an object of the invention is to provide an impact tool having an improved layout structure for the internal elements of an impact tool, which can suppress the vibration of the whole impact tool.
• the present invention provides an impact tool comprising:
• a piston adapted to reciprocately move in the cylinder
• a striker adapted to follow the movement of the piston in the cylinder
• a tool bit adapted to be impacted by the striker to move forwardly in the tool holder; wherein the cylinder and the tool holder are mechanically separated from each other radially.
• the cylinder and the tool holder are each fixed in the house radially by press fit or form fit with the house or by fasteners.
• the impact tool further comprises an air spring disposed in the cylinder between the striker and the piston.
• the tool bit is impacted by the striker via a striker plunger which is slidably disposed in the tool holder.
• the impact tool further comprises a first damping ring arranged axially between the cylinder and the tool holder.
• the cylinder is fixed in the housing axially by means of the tool holder, while the tool holder is fixed in the housing axially between the cylinder and a single fastener, such as a circlip.
• the impact tool may further comprise a second damping ring arranged between the fastener and the tool holder.
• the cylinder and the tool holder are also mechanically separated from each other axially.
• the tool holder is fixed in the housing axially by means of: fasteners disposed at different axial positions; or a shoulder formed in the housing and a fastener disposed at a different axial position.
• the tool holder comprises a front portion for guiding the tool bit and a back portion having an enlarged diameter for guiding the striker plunger, a shoulder being formed between the front portion and the back portion and acting as a stop for limiting the forward movement of the striker plunger.
• the impact tool of the invention is preferably a portable impact tool, such as an impact chisel, a hammer, an impact drill, or the like.
• the invention provides an impact tool having a new layout structure for its internal elements which mechanically decouples or separates the tool bit and its tool holder from the piston and the cylinder at least in axial direction.
• at least the axial component of the vibration of the tool bit is not easy to be transmitted to the piston and the cylinder, which helps to suppress the vibration level of the whole impact tool.
• Fig. 1 is a schematic cross-sectional view of an impact tool according to a first embodiment of the invention, showing an operation stage of the impact tool;
• Fig. 2 is a schematic cross-sectional view of the impact tool of Fig. 1, showing a later operation stage;
• Fig. 3 is a schematic cross-sectional view of an impact tool according to a second embodiment of the invention, showing an operation stage of the impact tool;
• Fig. 4 is a schematic cross-sectional view of the impact tool of Fig. 3, showing a later operation stage.
• a first embodiment of the impact tool according to the invention comprises a housing 1, which is preferably made of a material having high strength, high durability, and vibration damping ability.
• a cylinder 2 is fixedly mounted in the housing 1.
• a piston 4 is disposed in the cylinder 2, being reciprocately slidable in the cylinder in the axial direction.
• the piston is kinetically coupled to and driven by a motor (not shown), such as an electric, pneumatic or hydraulic motor.
• the piston is coupled with the motor via a crankshaft mechanism.
• One or more sealing rings 4a are arranged on the circumferential surface of the piston 4 to seal the piston against the inner wall of the cylinder 2.
• a striker 6 is disposed in the cylinder 2, forwardly of the cylinder 2.
• the striker 6 is also reciprocately slidable therein in the axial direction of the cylinder.
• the striker 6 has a back portion 6-2 which is guided by the inner wall of the cylinder 2 and a front portion 6-1 with a reduced outer diameter and acting as a striking portion.
• the front portion 6-1 may be formed integrally with the back portion 6-2.
• the front portion 6-1 may be formed separately and assembled to the back portion 6-2. In this case, the front portion 6-1 may be formed of different materials with the back portion 6-2.
• striker 6 may have a constant outer diameter.
• One or more sealing rings 6a are arranged on the circumferential surface of the back portion 6-2 of the striker 6 to seal the striker against the inner wall of the cylinder 2.
• An air spring 8 is disposed in the cylinder 2 between the striker 6 and the piston 4.
• the air spring 8 is formed by air contained in the space defined inside the cylinder 2 between the rear end surface of the striker 6 and the front end surface of the piston 4. By means of the air spring 8, the striker 6 will follow the reciprocating movement of the piston 4, without contacting the later.
• a tube like tool holder 10 is also fixedly mounted in the housing 1, being coaxial with the cylinder 2.
• a tool bit 12, such as a chisel bit, a drill bit, or the like, is held by and guided in the tool holder 10, being slidable axially in the tool holder.
• the tool bit 12 has a guided middle portion 12-1 which is guided by the tool holder 10 so that the tool bit 12 is reciprocately moveable in the axial direction of the tool holder, a front end (not shown) which is protruded forwardly from the middle portion to a point outside the housing 1 and acts as a working end to perform operation to a workpiece, and a back end 12-2 which is protruded backwardly from the middle portion and configured to be impacted by the striker 6.
• the tool bit 12 is impacted by the striker 6 indirectly via a striker plunger 14.
• the tool holder 10 comprises two portions, a front portion 10-1 for guiding the tool bit 12 and a back portion 10-2 having an enlarged diameter for guiding the striker plunger 14.
• a shoulder 10a is formed between the front portion 10-1 and the back portion 10-2.
• the shoulder 10a has an inner surface which acts as a stop for limiting the forward movement of the striker plunger 14.
• the inner surface of the shoulder 10a may be formed as a conical surface as shown, or be formed as a planar surface perpendicular to the central axis of the tool holder 10.
• the outer surface of the shoulder 10a is formed as a forwardly faced abutting surface, by means of which the tool holder 10 is retained in the housing 1 in the axial direction, as will be described.
• the striker plunger 14 has a front portion 14-1 which is guided in the back portion 10-2 of the tool holder 10 and a back portion 14-2 which has a reduced outer diameter and configured to be impacted by the striker 6.
• the back portion 14-2 may be formed integrally with the front portion 14-1. Alternatively, the back portion 14-2 may be formed separately and assembled to the front portion 14-1. In this case, the back portion 14-2 may be formed of different materials with the front portion 14-1.
• striker plunger 14 may have a constant outer diameter.
• One or more sealing rings 14a are arranged on the circumferential surface of the front portion 14-1 of the striker plunger 14 to seal the striker plunger against the inner wall of the back portion 10-2 of the tool holder 10.
• the front portion 14-1 of the striker plunger 14 is preferably formed with a forwardly opened recess 14b for receiving the back portion 12-2 of the tool bit 12.
• the striker plunger is omitted and the tool bit 12 is impacted by the striker 6 directly.
• the tool holder 10 may be formed as having a constant inner diameter.
• the striker 6, at least its back portion 6-2, is formed of metal so that it has enough inertial to generate desired impact force on the striker plunger (or on the tool bit directly).
• the front end of the cylinder 2 is formed with an outwardly protruded flange 2-1 which biases against a shoulder la formed within the housing 1.
• a first gasket 16, a first damping ring 20 and a second gasket 18 are clamped in serial between the back end of the tool holder 10 and the flange 2-1 of the cylinder 2.
• a second damping ring 22 is arranged to abut the forwardly faced outer surface of the shoulder 10a, a washer 24 is arranged to abut the front surface of the second damping ring 22, and a circlip 26 is clamped between the front surface of the washer 24 and a corresponding clamping portion lb of the housing 1.
• the first damping ring 20 and the second damping ring 22 are both compressed in the axial direction.
• the flange 2-1 of the cylinder 2 is clamped in the axial direction between the second gasket 18 and the shoulder la of the housing 1, so that the cylinder 2 is fixed in the housing 1 in the axial direction.
• the cylinder 2 fixed in the housing 1 in the radial direction by means of press fit or form fit between the cylinder 2 and the housing 1.
• fasteners can be used for fixing the cylinder in the housing.
• the back portion 10-2 of the tool holder 10 is clamped in the axial direction between the first gasket 16 and the second damping ring 22, so that the tool holder 10 is fixed in the housing 1 in the axial direction.
• the tool holder 10 fixed in the housing 1 in the radial direction by means of press fit or form fit between the tool holder 10 and the housing 1.
• fasteners can be used for radially fixing the tool holder in the housing.
• the cylinder 2, the piston 4, the striker plunger 14 and the tool holder 10 may each be formed of plastic, metal, or other materials known in the art.
• the forward most position of the striker plunger 14 (see Fig. 2) is defined when the front end of the striker plunger 14 contacts the inner surface of the shoulder 10a of the tool holder 10, and the backward most position of the striker plunger 14 (see Fig. 1) is defined when the back end of the front portion 14-1 of the striker plunger 14 contacts the front surface of the first gasket 16.
• the striker plunger 14 moves reciprocately between its forward and backward most positions.
• the forward most position of the striker 6 (see Fig. 2) is defined when the front end of the back portion 6-2 contacts the back surface of the second gasket 18, and the backward most position of the striker 6 (not shown) is defined when the striker 6 is stopped by the pushing force of the air spring 8 during the backward movement of the striker 6.
• the piston 4 is driven by the driver to move forwardly (towards the striker 6, as shown by arrow F in Fig. 1) and creates a pushing force to the striker 6 via the air spring 8.
• the striker 6 thus moves forwardly and results in that the front portion 6-1 of the striker 6 impacts the back portion 14-2 of the striker plunger 14 (see Fig. 1).
• the striker plunger 14 pushes the tool bit 12 to move forwardly (as shown by arrow F in Fig. 2).
• the striker plunger 14 and the striker 6 are blocked at their forward most positions by the inner surface of the shoulder 10a of the tool holder 10 and the second gasket 18 respectively, while the tool bit 12 continues to move forwardly to operate on a workpiece.
• the piston 4 is driven by the driver to move backwardly (in a direction opposite to arrow F) and thus creates a pulling force to the striker 6 via the air spring 8.
• the striker 6 is thus moved backwardly.
• the tool bit 12 reaches to the end of its forward movement by the reaction force applied by the workpiece in the backward direction, and then moves backwardly under the reaction force.
• returning means such as a returning spring, may help to move the tool bit 12 backwardly.
• the tool bit 12 reaches the striker plunger 14 and pushes it to its backward most position where it is blocked by the first gasket 16.
• a first damping ring 20 is arranged between the tool holder 10 and the cylinder 2.
• the axial component of the vibration of the tool bit 12 will be absorbed by the first damping ring, and only a small proportion of the axial component of the vibration of the tool bit 12 can be transmitted to the cylinder 2 via the tool holder 10.
• the second damping ring and the housing also absorb some of the vibration of tool bit.
• the tool holder 10 and the cylinder 2 are clamped in the housing 1 in the radial direction by means of the single circlip 26.
• the assembling and dissembling of the tool holder 10 and the cylinder 2 can be achieved by simply attaching and removing the circlip 26 to and from the housing 1 respectively.
• the front end of the cylinder 2 is not formed with an outwardly protruded flange 2-1 as that of the first embodiment.
• the cylinder 2 and the tool holder 10 of the second embodiment are fixed in the housing 1 separately from each other.
• the cylinder 2 is fixed in the housing 1 in both radial and axial direction by means of press fit or form fit between the cylinder 2 and the housing 1.
• one or more fasteners may be used for fixing the cylinder 2 in the housing 1.
• a retainer 28 is added for clamping the back end of the tool holder 10.
• the retainer 28 may by a circlip, like the circlip 26 which clamps the front end of the tool holder 10.
• a washer 24 and a second damping ring 22 are arranged between the circlip 26 and the outer surface of the shoulder 10a of the tool holder 10, and a first gasket 16, a first damping ring 20 and a second gasket 18 are clamped between the tool holder 10 and the retainer 28.
• the retainer 28 may be replaced by a shoulder formed within the housing 1, which is similar to the shoulder la shown in Figs. 1 and 2, but formed at a location forwardly beyond the front end of the cylinder 2.
• the tool holder 10 fixed in the housing 1 in the radial direction by means of press fit or form fit between the tool holder 10 and the housing 1.
• fasteners can be used for radially fixing the tool holder in the housing.
• Fig. 3 shows the backward most position of the striker plunger 14
• Fig. 4 shows the forward most positions of the striker plunger 14 and the striker 6.
• the second embodiment there is no mechanical coupling between the tool holder 10 and the cylinder 2 in either the radial direction or the axial direction, thus neither the radial and the axial components of the vibration of the tool bit 12 can be transmitted to the cylinder 2 as well as to the striker 6 and the piston 4 arranged in the cylinder 2.
• the layout structure of the tool holder 10 and the cylinder 2 as shown in Figs. 3 and 4 is mechanically decoupled or separated in both the radial and axial directions, that is to say, no mechanical force or action can be transmitted in either the radial direction or the axial direction from the tool holder 10 to the cylinder 2 directly.
• the first and second damping rings and the housing also absorb some of the vibration of tool bit. Thus, the vibration of the whole impact tool can be reduced to a level even lower than in the first embodiment.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Percussive Tools And Related Accessories (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=46506744

Family Applications (1)

Country Status (2)

Cited By (3)

Citations (5)

Family Cites Families (7)

• 2011
  • 2011-01-10 WO PCT/CN2011/070129 patent/WO2012094800A1/en active Application Filing
  • 2011-01-10 CN CN201180065732.3A patent/CN103328159B/zh active Active

Patent Citations (6)

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