JP2013144346A - Hammer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a cylinder case and a front cover of a hammer without using a bolt.SOLUTION: A hammer 1 is provided for fixing a front cover 6 for holding a tip tool 40 to a cylinder case 5, and includes a projection 60 formed on an outer surface of the front cover 6 and abutting on an end surface 62 of the cylinder case 5 for inserting the front cover 6, and a fixing member 70 arranged by straddling an abutting surface between the projection 60 and the end surface 62. A side surface of the fixing member 70 is joined to the cylinder case 5 with a screw, a bottom surface of the fixing member 70 is opposed to the end surface 62 by sandwiching the projection 60, an elastic body 78 is arranged between the bottom surface of the fixing member 70 and the projection 60, and the front cover 6 is prevented from rotating with respect to the cylinder case 5.

Description

  The present invention relates to a striking tool used when processing concrete, brick, stone, asphalt, or the like, such as crushing, grinding, chipping or drilling.

  A typical striking tool has an electric motor, a cylinder, a piston and a striking element disposed in the cylinder, and a conversion mechanism that converts the rotational motion of the electric motor into reciprocating motion of the piston, and is compressed by the piston. The reaction force of the air in the cylinder (air spring) is transmitted to the tip tool via the striker (see Patent Document 1).

  In the impact tool having the above-described configuration, the front cover holding the tip tool is fixed to the tip of the cylinder case in which the cylinder is accommodated. Specifically, a flange formed at the rear end of the front cover is abutted against the front end surface of the cylinder case, and the flange is fixed to the front end surface of the cylinder case by a bolt passing through the flange.

JP 2004-130470 A

  In order to fix the cylinder case and the front cover with bolts, it is necessary to form a flange on at least one of the two, and it is necessary to form a through hole for passing the bolt through the flange. And in order to make the flange as small as possible while securing the area for forming the through hole, the outer shape of the flange has to be made square. However, the square flange is difficult to fit in the hand, and the holdability of the conventional impact tool is not always good.

  An object of the present invention is to provide an impact tool in which a cylinder case and a front cover are fixed without using bolts.

  The striking tool of the present invention includes a motor, a striking mechanism that converts a rotational motion of the motor into a reciprocating motion and transmitting a striking force to a tip tool, a cylinder case that houses at least a part of the striking mechanism, and the cylinder A striking tool that is fixed to the case and has a front cover that holds the tip tool, provided on the outer surface of the front cover, and a projecting portion that contacts the end surface of the cylinder case into which the front cover is inserted. A fixing member disposed across a contact surface between the projecting portion of the front cover and the end surface of the cylinder case, and a side surface of the fixing member is screwed to the cylinder case and fixed. The bottom surface of the member faces the end surface of the cylinder case with the protruding portion of the front cover interposed therebetween, and the bottom surface of the fixing member and the front cover Is disposed an elastic body between the projection of over, the front cover is prevented from rotating relative to the cylinder casing.

  In the impact tool of the present invention, a female screw that is coupled to a male screw formed on the outer surface of the cylinder case is formed inside the side surface of the fixing member.

  In the impact tool of the present invention, the inner surface of the corner portion connecting the side surface and the bottom surface of the fixing member is a curved surface.

  In the impact tool of the present invention, the inner surface and the outer surface of the corner are curved surfaces.

  The striking tool of the present invention includes a convex portion formed at a portion of the front cover inserted into the cylinder case, and a concave portion formed inside the cylinder case, and the convex portion and the concave portion. Are engaged with each other.

  The striking tool of the present invention has a recess formed in a portion of the front cover that is inserted into the cylinder case, and a protrusion formed inside the cylinder case, and the recess and the protrusion Are engaged with each other.

  The striking tool of the present invention has a first plane formed on the outer surface of the portion of the front cover inserted into the cylinder case, and a second plane formed on the inner surface of the cylinder case. The first plane and the second plane face each other.

  In the impact tool of the present invention, the elastic body is rubber.

  According to the present invention, an impact tool in which a cylinder case and a front cover are fixed without using a bolt is realized.

It is a fragmentary sectional view showing an example of an embodiment of an impact tool of the present invention. It is a partial front view of the impact tool shown in FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is AA sectional drawing of FIG.

  Hereinafter, an exemplary embodiment of the impact tool of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the impact tool 1 according to the present embodiment includes a motor housing 2, a handle 3 provided behind the motor housing 2, a crankcase 4 provided above the motor housing 2, A cylinder case 5 and a front cover 6 fixed to the tip of the cylinder case 5 are provided.

  The motor housing 2 houses an electric motor 10 as a power source. A rotating shaft 11 of the electric motor 10 is rotatably supported by a bearing 12 provided in the motor housing 2. The rotating shaft 11 is provided with a gear 13, and the gear 13 is connected to a striking mechanism. A gear 21 meshed with a gear 13 provided on the rotating shaft 11 of the electric motor 10 is provided at one end of the crankshaft 20 constituting a part of the striking mechanism so as to be integrally rotatable. The rotary plate 22 is provided so as to be integrally rotatable. The rotation plate 22 is provided with a crank pin 23 at a position eccentric from the rotation center of the rotation plate 22, and one end of a connecting rod 24 is rotatably connected to the crank pin 23. The number of teeth of the gear 21 provided on the crankshaft 20 is greater than the number of teeth of the gear 13 provided on the rotating shaft 11 of the electric motor 10, and the gear 13 and the gear 21 constitute a reduction mechanism. ing.

  The cylinder case 5 has a cylindrical shape with one axial end (tip) opened. A cylinder 30 having a cylindrical shape is accommodated in the cylinder case 5. Inside the cylinder 30, a piston 31, a striker (sometimes called “striker”) 32, and a meson 33 are arranged in this order along the axis of the cylinder 30, and part of the meson 33 is a cylinder. Projecting outward from the tip of 30. A flange 33 a is formed at the end of the intermediate element 33 protruding from the cylinder 30, and the flange 33 a protrudes outside the cylinder case 5 through the opening of the cylinder case 5.

  The piston 31, the striker 32, and the intermediate member 33 can reciprocate in the cylinder 30, and the other end of the connecting rod 24 whose one end is connected to the crank pin 23 is connected to the piston 31. Further, O-rings are fitted on the outer peripheral surfaces of the piston 31, the striker 32, and the intermediate element 33, respectively, and the airtightness of the cylinder 30 is maintained by these O-rings.

  When the trigger switch 7 provided on the handle 3 is operated, the electric motor 10 is driven and the rotary shaft 11 rotates. The rotation of the rotating shaft 11 is transmitted to the crankshaft 20 through the speed reduction mechanism, and the crankshaft 20 rotates. When the crankshaft 20 rotates, the rotating plate 22 rotates, and the crank pin 23 on the rotating plate 22 rotates around the rotation center of the rotating plate 22. When the crank pin 23 rotates, the connecting rod 24 reciprocates, and accordingly, the piston 31 reciprocates within the cylinder 30. That is, the rotational motion of the electric motor 10 is converted into the reciprocating motion of the piston 31. When the piston 31 reciprocates in the cylinder 30, the compression and expansion of air in the air chamber 34 between the piston 31 and the striker 32 are continuously repeated. As a result, a striking force is applied to the intermediate element 33 via the striking element 32. At this time, the air in the air chamber 34 functions as an air spring.

  The front cover 6 has a cylindrical shape with both axial ends open, and the shaft portion 41 of the tip tool 40 is inserted and held therein. This will be specifically described below. A relatively thin part and a thick part are formed in the shaft part 41 of the tip tool 40. In the following description, in the shaft portion 41 of the tip tool 40, a portion having a relatively small diameter is referred to as “neck portion 41a”, and a portion having a relatively large diameter is referred to as “large diameter portion 41b”. is there. However, such a distinction is merely a distinction for convenience of explanation.

  In the present embodiment, at least two large-diameter portions 41b are respectively formed before and after the constricted portion 41a. The large-diameter portion 41b has a substantially hexagonal cross-sectional shape, and the constricted portion 41a has a substantially circular cross-sectional shape. As shown in FIG. 2, projections 42 extending in the axial direction are formed at the six corners of the large diameter portion 41 b, and the projections 42 are fitted on the inner peripheral surface of the front cover 6. A matching groove 50 is formed. The tip tool 40 is prevented from rotating with respect to the front cover 6 by the engagement between the protrusion 42 and the groove 50.

  Refer to FIG. 1 again. On the outer peripheral surface of the front cover 6, an annular first stopper 51 and an annular second stopper 52 are provided at an interval. The first stopper 51 in the present embodiment is a protrusion formed on the outer peripheral surface of the front cover 6 and is integrally formed with the front cover 6. On the other hand, the second stopper 52 in the present embodiment is a ring fitted on the outer peripheral surface of the front cover 6, and is a separate member from the front cover 6. However, both the first stopper 51 and the second stopper 52 may be integrally formed with the front cover 6. Further, both the first stopper 51 and the second stopper 52 may be formed by members separate from the front cover 6.

  Between the first stopper 51 and the second stopper 52, a pair of holes 53 that penetrates the front cover 6 in the radial direction are formed, and metal balls 54 are accommodated in the respective holes 53. . The outer diameter of the ball 54 is slightly smaller than the inner diameter of the hole 53, and the ball 54 can move in the radial direction of the front cover 6 inside the hole 53.

  Further, a cylindrical grip 55 is put on the outer peripheral surface of the front cover 6, and a pressing portion 55 a is provided on the bottom surface of the grip 55 facing the outer peripheral surface of the front cover 6. The grip 55 is placed on the front cover 6 such that a pressing portion 55 a is disposed between the first stopper 51 and the second stopper 52. Therefore, the grip 55 can slide on the outer peripheral surface of the front cover 6 along the axis of the front cover 6 within a range in which the pressing portion 55 a can move between the first stopper 51 and the second stopper 52. . However, a spring 56 is disposed between the pressing portion 55 a and the first stopper 51, and the pressing portion 55 a (grip 55) is constantly urged toward the second stopper 52 by the elastic restoring force of the spring 56. Yes. In the following description, the grip position when the pressing portion 55a is in contact with the second stopper 52 (the state shown in FIG. 1) may be referred to as a “fixed position”. When the grip 55 is in the fixed position, the pressing portion 55 a is located above the hole 53 and is in contact with the ball 54. Therefore, when the grip 55 is in the fixed position, the movement of the ball 54 in the radial direction of the front cover 6 is restricted. For this reason, even if a force in the axial direction of the front cover 6 acts on the tip tool 40, the large-diameter portion 41b of the shaft portion 41 is caught by the ball 54, and the movement of the tip tool 40 in the same direction is restricted. The However, the constricted portion 41a of the shaft portion 41 has a certain length. Therefore, the tip tool 40 is movable back and forth in the axial direction of the front cover 6 within the range of the length of the constricted portion 41a.

  On the other hand, when the grip 55 in the fixed position is moved against the bias of the spring 56 (sliding), the pressing portion 55 a is retracted from the hole 53. In the following description, the grip position when the pressing portion 55a is retracted from the hole 53 may be referred to as a “release position”. When the grip 55 is moved to the release position, the movement restriction on the ball 54 is released, and the ball 54 can move in the radial direction of the front cover 6. Therefore, the tip tool 40 can be pulled out from the front cover 6.

  As shown in FIG. 1, the front cover 6 is fixed to the tip of the cylinder case 5, and the shaft portion 41 of the tip tool 40 held by the front cover 6 is inserted into a holding hole 33 b provided in the intermediate piece 33. Inserted and connected to the meson 33. As a result, the striking force applied to the intermediate element 33 is transmitted to the tip tool 40.

  Hereinafter, a fixing structure between the cylinder case 5 and the front cover 6 will be described in detail. In the cylinder case 5 and the front cover 6, the rear end of the front cover 6 is inserted into the front end of the cylinder case 5, and the flange 33 a of the intermediate element 33 protruding from the front end of the cylinder case 5 is formed at the rear end of the front cover 6. They are fixed to each other in the inserted state.

  On the outer peripheral surface of the front cover 6 and in the vicinity of the rear end of the front cover 6, a flange-like protrusion 60 is formed over the entire periphery. Further, the rear end portion of the front cover 6 (the portion behind the projecting portion 60) is formed to be thinner than the inner diameter of the opening of the cylinder case 5 and larger than the outer diameter of the flange 33a of the intermediate element 33, and The cylinder 5 is inserted from the opening of the case 5 into the cylinder case 5. In the following description, the rear end portion of the front cover 6 inserted inside the cylinder case 5 may be called an “insertion portion 61” to be distinguished from other portions. However, such a distinction is merely a distinction for convenience of explanation.

  The insertion portion 61 of the front cover 6 is inserted from the opening of the cylinder case 5 between the inner peripheral surface of the cylinder case 5 and the outer peripheral surface of the flange 33 a of the intermediate element 33. As a result, the flange 33 a of the intermediate element 33 is inserted inside the front cover 6. At this time, the inner peripheral surface of the cylinder case 5 and the outer peripheral surface of the front cover 6 face each other with almost no gap, and the inner peripheral surface of the front cover 6 and the outer peripheral surface of the flange 33a face each other with almost no gap. Further, the projecting portion 60 provided on the outer peripheral surface of the front cover 6 is in contact with the periphery (end surface 62) of the opening of the cylinder case 5. In other words, the front cover 6 is inserted into the cylinder case 5 until the protruding portion 60 contacts the end surface 62 of the cylinder case 5.

  As shown in FIG. 3, a pair of convex portions 63 are formed on the outer peripheral surface of the insertion portion 61 of the front cover 6 at positions different by 180 degrees. Each convex portion 63 is elongated along the axis of the insertion portion 61. On the other hand, a pair of recesses 64 are formed on the inner peripheral surface of the cylinder case 5 at positions different by 180 degrees. Each recess 64 is formed to be elongated along the axis of the cylinder case 5. And the convex part 63 formed in the insertion part 61 of the front cover 6 is fitted in the concave part 64 formed in the cylinder case 5. The front cover 6 is prevented from rotating with respect to the cylinder case 5 by the engagement between the convex portion 63 and the concave portion 64.

  Refer to FIG. 1 again. On the outer peripheral surfaces of the cylinder case 5 and the front cover 6, a metal fixing member 70 (made of steel in this embodiment) is disposed so as to straddle both. The fixing member 70 has a cylindrical side wall 71 that forms a side surface, and a flange portion 75 that forms a bottom surface that is connected to one end of the side surface. 4) is formed. More specifically, a through hole 74 through which the front cover 6 can be passed is formed at the bottom of the fixing member 70, and the flange extends in parallel with the opening surface of the through hole 74 from the edge of the through hole 74. The part 75 extends. A side wall 71 extends from the edge of the flange portion 75 substantially at right angles to the opening surface of the through hole 74. That is, the flange portion 75 and the side wall 71 are continuous via the corner portion 76. The inner surface of the corner portion 76 connecting the edge of the flange portion 75 and the edge of the side wall 71 is formed in a curved surface.

  The side wall 71 of the fixing member 70 straddles the contact surface between the end surface 62 of the cylinder case 5 and the protruding portion 60 of the front cover 6, and the flange portion 75 of the fixing member 70 sandwiches the protruding portion 60 of the front cover 6. It faces the end face 62 of the cylinder case 5. Furthermore, a female screw 72 formed on the inner surface of the side wall of the fixing member 70 is coupled to a male screw 77 (FIGS. 3 and 4) formed on the outer peripheral surface of the cylinder case 5. In addition, an annular urethane rubber 78 as an elastic body is disposed between the flange portion 75 of the fixing member 70 and the protruding portion 60 of the front cover 6. In other words, the flange portion 75 of the fixing member 70 fixed to the cylinder case 5 by the coupling of the male screw 77 and the female screw 72 is urethane rubber between the flange portion 75 and the end surface 62 of the cylinder case 5. A projecting portion 60 of the front cover 6 is sandwiched via 78. The outer diameter of the region where the male screw 77 is formed on the outer peripheral surface of the cylinder case is such that the outer peripheral surface of the cylinder case 5 and the outer peripheral surface of the fixing member 70 fixed to the cylinder case 5 are flush with each other. It is thinner than other parts.

  When the female screw 72 formed on the fixing member 70 is coupled to the male screw 77 formed on the cylinder case 5, the fixing member 70 is rotated about its axis and tightened with a specified torque. Therefore, as shown in FIG. 5, on the outer peripheral surface of the fixing member 70, two flat surfaces 79 for applying a dedicated tool or a general-purpose tool are formed at positions different from each other by 180 degrees.

  As described above, in the impact tool according to the present invention, the projecting portion of the front cover is sandwiched between the end surface of the cylinder case and the flange portion of the fixing member fixed to the cylinder case. And the front cover are fixed. Further, the fixing member is fixed to the cylinder case by a combination of a screw formed on the fixing member and a screw formed on the cylinder case. Therefore, it is not necessary to use a bolt or the like to fix the cylinder case and the front cover, and it is not necessary to provide a flange on the cylinder case or the front cover.

  Here, as a method of fixing the cylinder case and the front cover without using bolts, a structure in which screws are respectively formed on the inner peripheral surface of the cylinder case and the outer peripheral surface of the front cover, and these screws are coupled can be considered. However, in such a structure, since the front cover cannot be prevented from rotating with respect to the cylinder case, the front cover and the tip tool cannot be positioned around the axis.

  In the impact tool according to the present invention, the impact applied to the fixing member is alleviated by the elastic body arranged between the fixing member and the protruding portion of the front cover, so that the durability of the fixing member is improved. When the inner surface of the corner portion of the fixing member is formed in a curved surface, stress concentration in the fixing member is suppressed, and the durability of the fixing member is further improved. Moreover, when both the inner surface and outer surface of the corner | angular part of a fixing member are formed in the curved surface, the stress concentration in a fixing member is further suppressed.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the above embodiment, the front cover is prevented from rotating with respect to the cylinder case by the engagement between the convex portion formed in the insertion portion of the front cover and the concave portion formed in the cylinder case. However, a concave portion may be formed in the insertion portion of the front cover, and a convex portion may be formed in the cylinder case. Further, the front cover is placed against the cylinder case by making a first plane partially formed on the outer surface of the insertion portion of the front cover face a second plane partially formed on the inner surface of the cylinder case. You may stop it.

  The elastic body disposed between the flange portion of the fixing member and the protruding portion of the front cover is not limited to rubber. Further, when the elastic body is rubber, the rubber is not limited to urethane rubber. However, it is preferable that the elastic body has a Shore hardness of Hs90 or higher. In addition, the elastic body is more excellent in shock absorbing capability as the thickness thereof is larger. However, when the thickness of the elastic body increases, a large space is required to arrange the elastic body. Therefore, it is preferable to make the thickness of the elastic body about 5 mm from the viewpoint of making the arrangement space as small as possible while obtaining the necessary and sufficient shock absorbing capability. The thickness of the elastic body here means the dimension of the elastic body in the opposing direction of the flange portion of the fixing member and the protruding portion of the front cover.

  In the above embodiment, the tip tool is prevented from rotating with respect to the front cover by the engagement between the protrusion provided on the shaft portion of the tip tool and the groove provided on the front cover. However, the structure for preventing the tip tool from rotating with respect to the front cover is not limited to the above structure.

DESCRIPTION OF SYMBOLS 1 Impact tool 5 Cylinder case 6 Front cover 10 Electric motor 20 Crankshaft 24 Connecting rod 30 Cylinder 31 Piston 32 Impactor 33 Intermediate | middle element 40 Tip tool 60 Protrusion part 61 Insertion part 62 End surface 63 Convex part 64 Concave part 70 Fixing member 71 Side wall 72 Female screw 75 Flange part 76 Corner part 77 Male thread 78 Elastic body (urethane rubber)

Claims (7)

A motor,
A striking mechanism that converts the rotational motion of the motor into a reciprocating motion and transmits a striking force to the tip tool;
A cylinder case that houses at least a part of the striking mechanism;
An impact tool having a front cover fixed to the cylinder case and holding the tip tool,
A protrusion provided on an outer surface of the front cover and in contact with an end surface of the cylinder case into which the front cover is inserted;
A fixing member disposed across a contact surface between the projecting portion of the front cover and the end surface of the cylinder case,
A side surface of the fixing member is screwed to the cylinder case,
The bottom surface of the fixing member is opposed to the end surface of the cylinder case with the protruding portion of the front cover interposed therebetween.
An elastic body is disposed between the bottom surface of the fixing member and the protruding portion of the front cover,
The impact tool according to claim 1, wherein the front cover is prevented from rotating with respect to the cylinder case.   The striking tool according to claim 1, wherein a female screw that is coupled to a male screw formed on an outer surface of the cylinder case is formed inside the side surface of the fixing member.   The striking tool according to claim 1 or 2, wherein an inner surface of a corner portion connecting the side surface and the bottom surface of the fixing member is a curved surface.   The impact tool according to claim 3, wherein an outer surface of the corner portion is a curved surface.   The front cover has a convex portion formed in a portion inserted into the cylinder case and a concave portion formed inside the cylinder case, and the convex portion and the concave portion are fitted to each other. The impact tool according to any one of claims 1 to 4, wherein the impact tool is provided.   The front cover has a concave portion formed in a portion inserted into the cylinder case and a convex portion formed inside the cylinder case, and the concave portion and the convex portion are fitted to each other. The impact tool according to any one of claims 1 to 4, wherein the impact tool is provided.   A first plane formed on the outer surface of the portion of the front cover that is inserted into the cylinder case; and a second plane formed on the inner surface of the cylinder case; The impact tool according to any one of claims 1 to 4, wherein the second plane faces each other.