Work equipment

Abstract

To realize a work machine which achieves improvement of durability of a coil spring for biasing a striking part.SOLUTION: A driving machine 1A includes: a driver blade 32 which strikes a stopper; a coil spring 51 which is formed by a spirally coiled wire and may expand and contract in a vertical direction; a load receiving part which is disposed facing the coil spring 51 in the vertical direction and receives a biasing force of the coil spring 51; a plunger 31 which may be moved in the vertical direction by the biasing force of the coil spring 51; and a buffer member 80b disposed between the coil spring 51 and the load receiving part. The buffer member 80b includes: an interposition part interposed between a lower end part of the coil spring 51 and the load receiving part; and an insertion part which is inserted into the inner side of the lower end part of the coil spring 51. The lower end part of the coil spring 51 may move relative to the load receiving part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a working machine suitable for driving operations for driving fasteners such as nails and staples into mating materials such as wood and gypsum boards.

Background Art

[0002] As one of the working machines as described above, a driving machine having a striking part that is biased by a biasing member to strike a fastener is known. For example, Patent Document 1 describes a driving machine having a driver blade for striking a fastener and a coil spring (coil spring) for biasing the driver blade.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to extend the life of the working machine as described above, it is required to improve the durability of the coil spring.

[0005] An object of the present invention is to provide a working machine with improved durability of a coil spring that biases a striking part.

Means for Solving the Problems

[0006] The work machine includes a striking part for striking a fastener, a coil spring formed from a spirally wound wire that expands and contracts in a first direction, a load receiving part positioned opposite the coil spring in the first direction and receiving the biasing force of the coil spring, a movable part that can move in the first direction due to the biasing force of the coil spring, and a buffer member interposed between the coil spring and the load receiving part. The buffer member includes an interposing part interposed between the end of the coil spring in the first direction and the load receiving part, and an insertion part inserted inside the end of the coil spring. The end of the coil spring is movable relative to the load receiving part. [Effects of the Invention]

[0007] According to the present invention, a work machine is realized in which the durability of the coil spring that biases the striking part is improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of the driving machine. [Figure 2] This is an explanatory diagram showing the structure of the driving machine. [Figure 3] This is a perspective view of a plunger. [Figure 4] This is a perspective view showing the striking mechanism, biasing mechanism, and counterweight. [Figure 5] This is a cross-sectional view showing the striking mechanism, biasing mechanism, and counterweight. [Figure 6] This is a cross-sectional view showing the plunger and counterweight at bottom dead center. [Figure 7] This is a cross-sectional view showing the plunger and counterweight at top dead center. [Figure 8] This is a schematic, partially enlarged cross-sectional view showing the behavior of the lower end of the coil spring at the moment the plunger strikes the plunger damper. [Figure 9] This is a schematic, partially enlarged cross-sectional view showing the behavior of the lower end of the coil spring immediately after the plunger strikes the plunger damper. [Figure 10] This is a partially enlarged cross-sectional view showing one modified example of the cushioning member. [Figure 11] This is a partially enlarged cross-sectional view showing another variation of the cushioning member. [Figure 12] This is a partially enlarged cross-sectional view showing another variation of the cushioning member. [Figure 13] This is a partially enlarged cross-sectional view showing another variation of the cushioning member. [Figure 14] This is a partially enlarged cross-sectional view showing an example of a counterweight equipped with a regulating section. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a side view showing the external appearance of a nailing machine 1A, which is an example of a work machine according to the present invention. The nailing machine 1A shown in Figure 1 is suitable for nailing work, in which fasteners such as nails and staples are driven into a mating material such as wood or gypsum board.

[0010] The driving machine 1A has a housing 10 and a magazine 20. The housing 10 includes a mechanism housing 11, a handle 12, a motor housing 13, and a connecting section 14. One longitudinal end of the handle 12 and the motor housing 13 is connected to the mechanism housing 11, and the other longitudinal end of the handle 12 and the motor housing 13 is connected to the connecting section 14. In other words, the mechanism housing 11, the handle 12, the motor housing 13, and the connecting section 14 are a single unit.

[0011] The mechanism housing chamber 11 of the housing 10 has a roughly rectangular cylindrical shape overall. Here, the longitudinal direction of the mechanism housing chamber 11 shown in Figure 1 is defined as the "vertical direction," and the longitudinal direction of the handle 12 and motor housing chamber 13 is defined as the "front-to-back direction." Furthermore, the direction perpendicular to the vertical and front-to-back directions is defined as the "left-to-right direction." However, these definitions are merely for the sake of explanation.

[0012] According to the above definition, the handle 12 is located above the motor housing chamber 13 and extends rearward from one side (the rear side) of the mechanism housing chamber 11. On the other hand, the motor housing chamber 13 is located below the handle 12 and extends rearward from one side (the rear side) of the mechanism housing chamber 11. Further, the connecting portion 14 connects the rear end of the handle 12 and the rear end of the motor housing chamber 13.

[0013] The housing 10 is composed of two housing members formed of a synthetic resin such as nylon or polycarbonate. Specifically, the housing 10 including the mechanism housing chamber 11, the handle 12, the motor housing chamber 13 and the connecting portion 14 is formed by two housing members that are abutted against each other and fixed.

[0014] FIG. 2 is an explanatory view showing the internal structure of the driving machine 1A. In FIG. 2, one of the two housing members forming the housing 10 is omitted and the inside of the housing 10 is exposed. A plurality of screw bosses 15 are integrally formed on the inside of the housing member shown in FIG. 2. The two housing members are fixed to each other by a plurality of screws that penetrate the housing member not shown in FIG. 2 and are screwed to the screw bosses 15 of the housing member shown in FIG. 2.

[0015] Although not shown in the drawing, at least a part of the surface of the housing 10 is covered with a resin cover. Specifically, at least a part of the surface of the housing 10 is covered with a resin layer (elastomer layer) formed (laminated) on the housing 10 by double-layer molding (two-color molding).

[0016] Furthermore, the mechanism housing chamber 11 and the tip of the handle 12 are connected via a part of the resin cover covering the surface of the housing 10. That is, the mechanism housing chamber 11 and the handle 12 are connected via a soft member. As a result, the mechanism housing chamber 11 and the handle 12 are relatively movable, and vibration transmission from the mechanism housing chamber 11 to the handle 12 is suppressed or reduced.

[0017] The driving machine 1A has a striking mechanism 30 for striking the fasteners. The striking mechanism 30 includes a plunger 31 as a first movable part and a driver blade 32 as a striking part. The plunger 31 is movable in the vertical direction by the biasing force of a coil spring 51, which will be described later, and the driver blade 32 is attached to the plunger 31. Therefore, the plunger 31 as the first movable part and the driver blade 32 as the striking part move up and down together as a single unit. In this embodiment, the vertical direction corresponds to the first direction of the present invention and coincides with the expansion and contraction direction of the coil spring 51.

[0018] Figure 3 is an enlarged perspective view of the plunger 31. The plunger 31 has an integrally molded bottom portion 33, mounting portion 34, wall portion 35, cylindrical portion 36, and arm portion 37. The wall portion 35 is formed around the periphery of the bottom portion 33, extending over its entire circumference. The cylindrical portion 36 protrudes upward from approximately the center of the bottom portion 33. With the cylindrical portion 36 as the reference, the mounting portion 34 is located on the front side of the plunger 31, and the arm portion 37 is located on the rear side of the plunger 31.

[0019] The mounting portion 34 protrudes forward from the wall portion 35. The mounting portion 34 is inserted into a connection hole provided at the upper end of the driver blade 32 (see Figure 2). The arm portion 37 includes three arms (arm 37a, arm 37b, and arm 37c). Arms 37a and 37c extend downward, and arm 37b extends upward. The tips of each of the arms 37a, 37b, and 37c are bent approximately 90 degrees backward to form an engagement portion.

[0020] The magazine 20 shown in Figure 1 houses multiple fasteners that are struck by the driver blade 32 shown in Figure 2. The magazine 20 is equipped with a feeding mechanism (feeder) that supplies the multiple fasteners it houses one by one to the injection passage 21. The fasteners sent from the magazine 20 to the injection passage 21 are struck by the driver blade 32 moving downward within the injection passage 21 and ejected from the injection port, which is the exit of the injection passage 21.

[0021] As shown in Figure 2, the driving machine 1A is equipped with a mechanism for moving the striking mechanism 30. Specifically, the driving machine 1A is equipped with a drive mechanism 40 that moves the plunger 31 and driver blade 32 upward, and a biasing mechanism 50 that moves the plunger 31 and driver blade 32 downward. In other words, the drive mechanism 40 and the biasing mechanism 50 move the striking mechanism 30 in opposite directions.

[0022] The drive mechanism 40 includes a first gear 41, a second gear 42, and a third gear 43. The first gear 41, the second gear 42, and the third gear 43 are each rotatably supported.

[0023] The rotational driving force output from the motor 44 is input to the first gear 41 via a planetary gear type reduction mechanism 45. In other words, the first gear 41 is rotationally driven by the motor 44. The first gear 41 meshes with the second gear 42, and the second gear 42 meshes with the third gear 43. In other words, the second gear 42 meshes with both the first gear 41 and the third gear 43. Therefore, when rotational driving force is input to the first gear 41, the first gear 41, the second gear 42, and the third gear 43 rotate. One cam roller is provided on the front of both the first gear 41 and the third gear 43. Two cam rollers are provided on the front of the second gear 42.

[0024] The biasing mechanism 50 includes a coil spring 51 that expands and contracts in the vertical direction, and a guide shaft 52 inserted through the coil spring 51. The guide shaft 52 guides the expansion and contraction of the coil spring 51 when the coil spring 51 expands and contracts.

[0025] As shown in Figures 4 and 5, the coil spring 51 is formed from a spirally wound wire. The coil spring 51 has one end (first end 51a) in the vertical direction (first direction) and the other end (second end 51b) in the vertical direction (first direction). In the following description, the first end 51a of the coil spring 51 may be referred to as the "upper end 51a" and the second end 51b as the "lower end 51b".

[0026] As shown in Figure 2, the driving machine 1A is equipped with a counterweight 60 in addition to the striking mechanism 30. The counterweight 60, like the striking mechanism 30, is moved by a drive mechanism 40 and a biasing mechanism 50. However, the drive mechanism 40 moves the counterweight 60 downward, while the biasing mechanism 50 moves the counterweight 60 upward. Specifically, the drive mechanism 40 moves the striking mechanism 30 (plunger 31 and driver blade 32) upward while moving the counterweight 60 downward. On the other hand, the biasing mechanism 50 moves the striking mechanism 30 (plunger 31 and driver blade 32) downward while moving the counterweight 60 upward. In other words, the counterweight 60 is a second movable part that moves in the opposite direction to the plunger 31 and driver blade 32 under the biasing force of the coil spring 51. The vertical movement of the plunger 31, driver blade 32 and counterweight 60 will be explained in more detail later.

[0027] As shown in Figure 2, a bottom holder 71 is provided at the lower end of the mechanism housing chamber 11, and a top holder 72 is provided at the upper end of the mechanism housing chamber 11. As shown in Figures 4 and 5, the bottom holder 71 and the top holder 72 are connected by a pair of vertically extending frame members 70. Alternatively, the bottom holder 71 is fixed to the lower end of the pair of frame members 70, and the top holder 72 is fixed to the upper end of the pair of frame members 70.

[0028] The plunger 31 is positioned between the lower end 51b of the coil spring 51 and the bottom holder 71, and a ring-shaped elastic member 73 is positioned between the plunger 31 and the bottom holder 71. On the other hand, the counterweight 60 is positioned between the upper end 51a of the coil spring 51 and the top holder 72, and a ring-shaped elastic member 74 is positioned between the counterweight 60 and the top holder 72.

[0029] The elastic members 73 and 74 are formed from an elastic material such as rubber. The elastic member 73 receives the first movable part (plunger 31) which moves downward (to one side in the first direction) under the biasing force of the coil spring 51, and prevents damage or deformation of the bottom holder 71 due to collision with the plunger 31. On the other hand, the elastic member 74 receives the second movable part (counterweight 60) which moves upward (to the other side in the first direction) under the biasing force of the coil spring 51, and prevents damage or deformation of the top holder 72 due to collision with the counterweight 60. In the following description, the elastic member 73 may be referred to as the "plunger damper 73" and the elastic member 74 as the "weight damper 74".

[0030] As shown in Figure 5, the cylindrical portion 36 of the plunger 31 is inserted into the lower end 51b of the coil spring 51. Furthermore, the lower part of the guide shaft 52 is inserted into the cylindrical portion 36 of the plunger 31, which is inserted into the lower end 51b of the coil spring 51. The lower part of the guide shaft 52 passes through the plunger 31 and the plunger damper 73 and is connected to the bottom holder 71. As a result, the lower end 51b of the coil spring 51 is positioned opposite the bottom 33 of the plunger 31 in an upward and downward direction, and the bottom 33 becomes a load-bearing portion that receives the biasing force of the coil spring. However, a buffer member 80b is interposed between the bottom 33 of the plunger 31 and the lower end 51b of the coil spring 51. Details of the buffer member 80b will be explained later.

[0031] The counterweight 60 is formed in a rectangular tubular shape and is placed over the top of the coil spring 51. Inside the counterweight 60, there is a cylindrical portion 62 similar to the cylindrical portion 36 of the plunger 31.

[0032] The cylindrical portion 62 of the counterweight 60 is inserted into the upper end 51a of the coil spring 51. Furthermore, the upper part of the guide shaft 52 is inserted into the cylindrical portion 62 inserted into the upper end 51a of the coil spring 51. The upper part of the guide shaft 52 passes through the counterweight 60 and the weight damper 74 and is connected to the top holder 72. As a result, the upper end 51a of the coil spring 51 is positioned opposite the ceiling 61 of the counterweight 60 in the vertical direction, and the ceiling 61 becomes a load-bearing part that receives the biasing force of the coil spring. However, a second buffer member 80a is interposed between the ceiling 61 of the counterweight 60 and the upper end 51a of the coil spring 51. Details of the second buffer member 80a will be explained later. Also, in the following explanation, the buffer member 80b may be referred to as the "lower holder 80b" and the second buffer member 80a may be referred to as the "upper holder 80a".

[0033] Next, we will outline the operation of the driving machine 1A. When predetermined conditions are met, including the operation of the trigger lever 2 shown in Figure 2, power is supplied from the battery 3 to the motor 44 under the control of the controller 16. As previously described, the rotational driving force output from the motor 44 is input to the first gear 41. As a result, the first gear 41 rotates, the second gear 42 rotates in the opposite direction to the first gear 41, and the third gear 43 rotates in the same direction as the first gear 41.

[0034] As the first gear 41 rotates, the cam roller of the first gear 41 engages with the arm 37a (Figure 3) of the plunger 31, pushing the plunger 31 upward. As a result, the plunger 31 moves upward while compressing the coil spring 51.

[0035] Subsequently, while the cam roller of the first gear 41 is engaged with arm 37a, one of the cam rollers of the second gear 42 engages with arm 37b (Figure 3) of the plunger 31, further pushing the plunger 31 upward. After that, the engagement between the cam roller of the first gear 41 and arm 37a is released.

[0036] Next, while one cam roller of the second gear 42 is engaged with the arm 37b of the plunger 31, the other cam roller of the second gear 42 engages with the arm 37c (Figure 3) of the plunger 31, further pushing the plunger 31 upward.

[0037] Meanwhile, as the third gear 43 rotates, the cam roller of the third gear 43 engages with the counterweight 60, pushing the counterweight 60 downward. As a result, the counterweight 60 moves downward while compressing the coil spring 51.

[0038] As a result, the plunger 31 moves (rises) from the position shown in Figure 6 (bottom dead center) to the position shown in Figure 7 (top dead center), compressing the coil spring 51. Meanwhile, the counterweight 60 moves (descends) from the position shown in Figure 6 (bottom dead center) to the position shown in Figure 7 (top dead center), compressing the coil spring 51. Alternatively, the coil spring 51 is compressed from above and below by the plunger 31 and the counterweight 60, accumulating a restoring force (biasing force).

[0039] When the plunger 31 rises to top dead center, the engagement between the second gear 42 (Figure 2) and the plunger 31 is released. Also, the engagement between the third gear 43 (Figure 2) and the counterweight 60 is released. Then, the plunger 31 shown in Figure 7 moves downward due to the restoring force (biasing force) of the coil spring 51, and the driver blade 32 (Figure 2) attached to the plunger 31 also moves downward. From another perspective, the plunger 31 is a transmission member that transmits the biasing force of the coil spring 51 to the driver blade 32. On the other hand, the movement of the counterweight 60 shown in Figure 7 is restricted by a stopper and does not start moving simultaneously with the plunger 31 and the driver blade 32.

[0040] Subsequently, when the plunger 31 descends to its predetermined position, the restriction on the movement of the counterweight 60 is released. Then, the counterweight 60 is moved upward by the restoring force (biasing force) of the coil spring 51.

[0041] As described above, the plunger 31 and the counterweight 60 move in opposite directions to each other, reducing the recoil when the driver blade 32 strikes the stopper. Furthermore, the recoil reduction effect can be further enhanced by appropriately setting the timing of when the plunger 31 begins to descend and when the counterweight 60 begins to rise.

[0042] Furthermore, the driving machine 1A is equipped with a position detection switch operated by a counterweight 60 that moves up and down as described above. The position detection switch is pressed by the counterweight 60 when it reaches top dead center, and the position detection switch pressed by the counterweight 60 outputs a signal. The signal output from the position detection switch is input to the controller 16 via electrical wiring. Therefore, the controller 16 can determine whether or not the counterweight 60 has reached top dead center.

[0043] Next, the upper holder 80a and the lower holder 80b will be explained again. The upper holder 80a and the lower holder 80b shown in Figure 5, etc., have substantially the same shape and structure. Therefore, in the following explanation, the upper holder 80a and the lower holder 80b may be collectively referred to as "holder 80".

[0044] As shown in Figures 6 and 7, the holder 80 comprises an annular intervening portion 81 and a cylindrical insertion portion 82. More specifically, the insertion portion 82 has a cylindrical shape that rises from the intervening portion 81. In other words, the insertion portion 82 has a cylindrical shape that extends from the intervening portion 81 in a first direction. The intervening portion 81 and the insertion portion 82 are integrally formed of polyurethane. The insertion portion 82 is coaxial with the intervening portion 81 and has a smaller diameter than the intervening portion 81. Alternatively, the intervening portion 81 is a flange provided at one end of the insertion portion 82.

[0045] As previously described, the lower holder 80b is interposed between the plunger 31 and the lower end 51b of the coil spring 51. Specifically, the cylindrical portion 36 of the plunger 31, which is inserted into the lower end 51b of the coil spring 51 and into which the lower part of the guide shaft 52 is inserted, is inserted into the insertion portion 82 of the lower holder 80b. Alternatively, the guide shaft 52, the cylindrical portion 36 of the plunger 31, the insertion portion 82 of the lower holder 80b, and the lower end 51b of the coil spring 51 are arranged in this order from the inside to the outside in the radial direction.

[0046] As a result, the intervening portion 81, which is formed in a flange shape at one end of the insertion portion 82, is interposed between the lower end portion 51b of the coil spring 51 and the bottom portion 33 of the plunger 31. On the other hand, the insertion portion 82 is interposed between the lower end portion 51b of the coil spring 51 and the cylindrical portion 36 of the plunger 31.

[0047] When the compression of the coil spring 51 shown in Figure 7 is released, the coil spring 51 extends at high speed, moving the plunger 31 downward. Then, as shown in Figure 8, when the plunger 31 hits the plunger damper 73, the extension of the coil spring 51 is abruptly stopped. At this time, the collision between the lower end 51b of the coil spring 51 and the bottom 33 of the plunger 31 is avoided by the intervening portion 81 of the lower holder 80b, preventing damage or deformation of the lower end 51b of the coil spring 51. In addition, the radial movement of the lower end 51b is restricted by the insertion portion 82 of the lower holder 80b, preventing buckling of the lower end 51b. As a result, the durability of the coil spring 51 is improved.

[0048] Furthermore, while the coil spring 51 is made of metal, the lower holder 80b is made of polyurethane. Therefore, the coil spring 51 will not be damaged by contact with the lower holder 80b. For example, even if the inner circumference of the coil spring 51 comes into contact with the outer surface of the insertion part 82, the coil spring 51 will not be damaged. However, the material of the lower holder 80b is not limited to polyurethane; other elastic or soft materials can also be selected.

[0049] On the other hand, if the intervening portion 81 is too soft, it may not adequately prevent damage or deformation of the lower end portion 51b of the coil spring 51. For example, if the intervening portion 81 is too soft, the lower end portion 51b of the coil spring 51 may dig into the intervening portion 81. Therefore, it is preferable that the hardness of the lower holder 80b including the intervening portion 81 be HSA 85 to 95 or an equivalent hardness. Furthermore, it is preferable that the hardness of the plunger damper 73 and the weight damper 74 be HSA 75 to 90 or an equivalent hardness.

[0050] Here, the outer diameter of the insertion portion 82 of the lower holder 80b is smaller than the inner diameter of the coil spring 51. In other words, the insertion portion 82 of the lower holder 80b is loosely fitted to the lower end portion 51b of the coil spring 51. Another way of looking at it is that the outer circumferential surface of the insertion portion 82 faces the inner circumference of the coil spring 51 in a manner that allows it to contact the inner circumference of the coil spring 51.

[0051] On the other hand, the inner diameter of the insertion portion 82 of the lower holder 80b is larger than the outer diameter of the cylindrical portion 36 of the plunger 31. In other words, the cylindrical portion 36 of the plunger 31 is loosely fitted into the insertion portion 82 of the lower holder 80b. Another way to look at it is that there is clearance between the inner circumferential surface of the insertion portion 82 and the outer circumferential surface of the cylindrical portion 36.

[0052] In other words, the plunger 31, coil spring 51, and lower holder 80b are not engaged with each other and are not fixed to each other. Therefore, the lower holder 80b is movable relative to the bottom (load-receiving part) 33 of the plunger 31. Also, the lower end 51b of the coil spring 51 is movable relative to the bottom (load-receiving part) 33 of the plunger 31. Therefore, when the plunger 31 hits the plunger damper 73 and the extension of the coil spring 51 is abruptly stopped, the displacement (lifting) of the lower end 51b of the coil spring 51 as shown in Figure 9 is permitted. On the other hand, if the lower end 51b of the coil spring 51 were fixed to the plunger 31, no displacement of the lower end 51b of the coil spring 51 relative to the plunger 31 would be permitted at all. In that case, unnecessary force (mainly tensile force) would be applied to the coil spring 51. Such unnecessary force is one of the causes of accelerated deterioration of the coil spring 51.

[0053] As shown in Figures 6 and 7, the upper holder 80a is interposed between the counterweight 60 and the upper end 51a of the coil spring 51. Specifically, the cylindrical portion 62 of the counterweight 60, which is inserted into the upper end 51a of the coil spring 51 and into which the upper part of the guide shaft 52 is inserted, is inserted into the insertion portion 82 of the upper holder 80a. As a result, the intervening portion 81, which is formed in a flange shape at one end of the insertion portion 82, is interposed between the upper end 51a of the coil spring 51 and the ceiling 61 of the counterweight 60. On the other hand, the insertion portion 82 is interposed between the upper end 51a of the coil spring 51 and the cylindrical portion 62 of the counterweight 60. Similar to the relationship between the plunger 31, the coil spring 51 and the lower holder 80b, the counterweight 60, the coil spring 51 and the upper holder 80a are relatively movable relative to each other.

[0054] The upper holder 80a improves the durability of the coil spring 51 by performing the same action as the lower holder 80b, as explained with reference to Figures 8 and 9. Specifically, when the counterweight 60, which is moved at high speed by the uncompressed coil spring 51, collides with the weight damper 74, the collision between the upper end 51a of the coil spring 51 and the top 61 of the counterweight 60 is avoided by the intervening portion 81 of the upper holder 80a, preventing damage or deformation of the upper end 51a of the coil spring 51. In addition, the radial movement of the upper end 51a is restricted by the insertion portion 82 of the upper holder 80a, preventing buckling of the upper end 51a.

[0055] Since the upper holder 80a is made of the same material as the lower holder 80b, the coil spring 51 will not be damaged by contact with the upper holder 80a. Also, for the same reasons as the lower holder 80b, the hardness of the upper holder 80a is preferably HSA 85 to 95 or equivalent.

[0056] The present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. For example, the cushioning member may not engage with the movable part (plunger or counterweight), but may engage with the coil spring. An example of a cushioning member that engages with a coil spring is shown in Figures 10 and 11.

[0057] The insertion portion 82 of the lower holder 80b shown in Figures 10 and 11 includes a large-diameter portion 82a and a small-diameter portion 82b connected to the large-diameter portion 82a, which has a smaller diameter than the large-diameter portion 82a. Furthermore, the large-diameter portion 82a of the insertion portion 82 is press-fitted into the inside of the lower end portion 51b of the coil spring 51, and the outer circumferential surface of the large-diameter portion 82a is in contact with the inner circumference of the lower end portion 51b. In other words, the outer circumferential surface of the large-diameter portion 82a is a contact surface that is in contact with the inner circumference of the coil spring 51. As a result, the lower holder 80b is engaged with the lower end portion 51b of the coil spring 51. The lower holder 80b, which is engaged with the lower end portion 51b of the coil spring 51, has the effect of preventing or suppressing vibration of the coil spring 51 (especially vibration of the lower end portion 51b).

[0058] Furthermore, since the lower holder 80b is not engaged with the plunger 31, no unnecessary force is applied to the coil spring 51 as the plunger 31 moves.

[0059] Furthermore, the small-diameter portion 82b of the lower holder 80b shown in Figure 11 is tapered, with its outer circumferential surface inclined at 14 degrees relative to the outer circumferential surface of the large-diameter portion 82a. The tapered small-diameter portion 82b facilitates and ensures the reinsertion of the insertion portion 82 into the coil spring 51 when a part of the insertion portion 82 comes out of the coil spring 51 (for example, in the state shown in Figure 9). From the viewpoint of facilitating the reinsertion of the insertion portion 82 into the coil spring 51, it is preferable that the vertical length of the small-diameter portion 82b be about 1 / 3 to 1 / 2 of that of the large-diameter portion 82a.

[0060] The cushioning member may not engage with the coil spring, but may engage with the movable part (plunger or counterweight). An example of a cushioning member that engages with the movable part is shown in Figure 12.

[0061] As shown in Figure 12, the cylindrical portion 36 of the plunger 31 is press-fitted into the insertion portion 82 of the lower holder 80b. As a result, the lower holder 80b is engaged with the plunger 31. However, since the lower holder 80b is not engaged with the coil spring 51, no unnecessary force is applied to the coil spring 51 as the plunger 31 moves.

[0062] As can be seen from the above description, the modified versions of the lower holder 80b shown in Figures 10 to 12 are also applicable to the upper holder 80a in the above embodiment.

[0063] In the above embodiment, the intervening portion 81 and the insertion portion 82 of the holder 80 were integrally formed from the same material. However, the intervening portion 81 and the insertion portion 82 of the holder 80 may be formed separately. In this case, the intervening portion 81 may be formed from a material with excellent strength and durability (for example, polyurethane), while the insertion portion 82 may be formed from a material with high shock absorption and friction coefficient (for example, nitrile rubber or butyl rubber). Furthermore, the intervening portion 81 may be a multilayer structure including two or more layers with different hardnesses. In addition, either the upper holder 80a or the lower holder 80b in the above embodiment may be omitted.

[0064] In the above embodiment, the upper holder 80a and the lower holder 80b had the same shape and structure. However, the shape and structure of the upper holder 80a and the lower holder 80b do not have to be the same. Figure 13 shows an example of an upper holder 80a that can be combined with any of the lower holders 80b described so far, but whose structure differs from any of the lower holders 80b described so far.

[0065] The upper holder 80a shown in Figure 13 has a divided structure composed of multiple parts that are independent of each other. Specifically, the upper holder 80a shown in Figure 13 has a three-part structure composed of three parts: a first intervening part 81a, a second intervening part 81b, and an insertion part 82.

[0066] The cylindrical portion 62 of the counterweight 60 passes through the first intervening portion 81a, the second intervening portion 81b, and the insertion portion 82, which are arranged in a row. However, the cylindrical portion 62 of the counterweight 60 is press-fitted into the insertion portion 82, while it is loosely fitted into the first intervening portion 81a and the second intervening portion 81b. In other words, the insertion portion 82 is fixed to the counterweight 60 but not to the coil spring 51. On the other hand, the first intervening portion 81a and the second intervening portion 81b are not fixed to either the counterweight 60 or the coil spring 51.

[0067] When the upper holder 80a has the split structure described above, only a portion of the upper holder 80a contacts the coil spring 51. In the case of the upper holder 80a shown in Figure 13, the second intervening portion 81b and the insertion portion 82 can contact the coil spring 51, but the first intervening portion 81a does not contact the coil spring 51. Also, since the second intervening portion 81b is positioned above and below the coil spring 51, it receives a large impact from the coil spring 51. Therefore, the hardness of the second intervening portion 81b, which can contact the coil spring 51, is made higher than that of the first intervening portion 81a, which does not contact the coil spring 51. Specifically, the second intervening portion 81b is formed of a material having a hardness of HSA 85-95 or equivalent (for example, polyurethane). On the other hand, the first intervening portion 81a is formed of a material (for example, nitrile rubber or butyl rubber) that has lower hardness than the material of the second intervening portion 81b, and has higher shock absorption and friction coefficient.

[0068] Furthermore, since the insertion portion 82 does not face the coil spring 51 from above or below, it receives less impact from the coil spring 51 compared to the second intervening portion 81b. On the other hand, it is desirable for the insertion portion 82 to have a lower hardness so that it can effectively absorb the impact applied to the coil spring when it comes into contact with the coil spring 51. For this reason, the insertion portion 82 is also made of a material (for example, nitrile rubber or butyl rubber) that has lower hardness than the material of the second intervening portion 81b, and has high shock absorption and friction coefficient.

[0069] The insertion portion 82 of the upper holder 80a shown in Figure 13 has a stepped shape in which the outer diameter of the upper region is larger than the outer diameter of the lower region. In the lower region, a gap is provided between the outer surface of the insertion portion 82 and the inner surface of the coil spring 51, but in the upper region, the outer diameter of the insertion portion 82 and the inner diameter of the coil spring 51 are approximately equal. Therefore, frictional resistance occurs when the upper end portion 51a of the coil spring 51 moves relative to the upper region of the insertion portion 82. The outer diameter of the upper region of the insertion portion 82 of the upper holder 80a is larger than the outer diameter of the insertion portion 82 of the lower holder 80b, and the frictional resistance between it and the coil spring 51 is also larger.

[0070] After the compression of the coil spring 51 is released and the plunger 31 and counterweight 60 reach the bottom dead center, the coil spring 51 moves away from the plunger 31 at its lower end 51b and away from the counterweight 60 at its upper end 51a. At this time, the force of the upper end 51a is greater than the force of the lower end 51b. According to the embodiment shown in Figure 13, the outer diameter of the upper region of the insertion portion 82 of the upper holder 80a is larger than the outer diameter of the insertion portion 82 of the lower holder 80b, and the frictional resistance generated between the coil spring 51 and the upper end 51a is also larger. Therefore, the force of the upper end 51a is reduced by friction, and the separation distance from the counterweight 60 can be reduced. This makes it possible to suppress deterioration of the upper end 51a side of the coil spring 51.

[0071] The counterweight 60 shown in Figure 13 may be provided with a restricting portion to restrict the movement of the upper holder 80a. Figure 14 shows an example of a counterweight 60 provided with a restricting portion. The cylindrical portion 62 of the counterweight 60 shown in Figure 14 passes through the insertion portion 82 of the upper holder 80a. An annular restricting portion 63 with a diameter larger than the inner diameter of the insertion portion 82 is provided at the end of the cylindrical portion 62 that protrudes from the insertion portion 82. Alternatively, the insertion portion 82 is sandwiched between the intervening portion 81 (second intervening portion 81b) and the restricting portion 63, restricting its movement in the vertical direction (first direction). Another way of looking at it is that the upper holder 80a is sandwiched between the ceiling 61 of the counterweight 60 and the restricting portion 63, restricting its movement in the vertical direction (first direction). As a result, the upper holder 80a is more reliably prevented from falling off the counterweight 60. In particular, the insertion portion 82 is more reliably prevented from falling out of the cylindrical portion 62. In other words, the restricting portion 63 shown in Figure 14 functions as a retainer for the insertion portion 82.

[0072] The restricting portion 63 can be provided not only on the cylindrical portion 62 of the counterweight 60 shown in Figure 13, but also on the cylindrical portion 62 of the counterweight 60 shown in other drawings. Furthermore, the restricting portion 63 can also be provided on the cylindrical portion 36 of the plunger 31. By providing the restricting portion 63 on the cylindrical portion 36 of the plunger 31, the detachment of the lower holder 80b from the plunger 31 is more reliably prevented.

[0073] However, the upper end 51a of the coil spring 51 is subjected to a greater impact than the lower end 51b. Therefore, if the restricting portion 63 is to be provided on only one of the cylindrical portion 36 of the plunger 31 or the cylindrical portion 62 of the counterweight 60, it is desirable to provide the restricting portion 63 on the cylindrical portion 62 of the counterweight 60.

[0074] The shape of the restricting portion 63 is not limited to annular. For example, one or more claw-shaped restricting portions may be provided along the circumferential direction of the cylindrical portion 62.

[0075] Furthermore, in the above embodiment, the load-receiving portion is provided on the movable portion. However, the load-receiving portion may be a fixed member that does not move. For example, the counterweight 60 and weight damper 74, etc., from the embodiment shown in Figure 5 may be omitted, and the upper holder 80a may be placed between the coil spring 51 and the top holder 72. In this case, the top holder 72 acts as the load-receiving portion. [Explanation of Symbols]

[0076] 1A…Piercer, 2…Trigger lever, 3…Battery, 10…Housing, 11…Mechanism housing, 12…Handle, 13…Motor housing, 14…Connecting part, 15…Screw boss, 16…Controller, 20…Magazine, 21…Ejection path, 30…Impact mechanism, 31…Plunger, 32…Driver blade, 33…Bottom, 34…Mounting part, 35…Wall, 36…Cylinder, 37…Arm, 37a,37b,37c…Arm, 40…Drive mechanism, 41…First gear, 42…Second gear, 43…Third gear, 44…Motor, 45…Reduction mechanism, 50…Biasing mechanism, 51 ...coil spring, 51a...first end (upper end), 51b...second end (lower end), 52...guide shaft, 60...counterweight, 61...ceiling, 62...cylindrical section, 63...regulating section, 70...frame member, 71...bottom holder, 72...top holder, 73...elastic member (plunger damper), 74...elastic member (weight damper), 80...holder, 80a...second buffer member (upper holder), 80b...buffer member (lower holder), 81...intervening section, 81a...first intervening section, 81b...second intervening section, 82...insertion section, 82a...large diameter section, 82b...small diameter section

Claims

1. A striking part that performs a striking action to strike the fastener, A coil spring formed by spirally wound wire, which expands and contracts in a first direction, A load-receiving portion is positioned opposite the coil spring in the first direction and receives the biasing force of the coil spring, A movable part that can move in the first direction by the biasing force of the coil spring, It has a cushioning member interposed between the coil spring and the load-receiving portion, The cushioning member is An intervening portion having an outer diameter larger than the inner diameter of the coil spring and interposed between the end of the coil spring in the first direction and the load-receiving portion, The device comprises an insertion portion that extends from the intervening portion toward the load-receiving portion, has an outer diameter smaller than the inner diameter of the coil spring, and is formed in a cylindrical shape with an outer diameter that is substantially constant over at least one turn of the coil spring in the first direction, and is inserted into the inside of the end of the coil spring, During the striking action, the end of the coil spring contacts the intervening portion when the coil spring is compressed, and is able to separate from the intervening portion when the coil spring returns to its original state. A work machine in which, during the striking operation, the inner circumference of the coil spring is able to contact the outer circumference of the insertion part while being separated from the intervening part, and is also able to move relative to it in the first direction.

2. The work machine according to claim 1, wherein the insertion portion has a cylindrical shape that rises from the intervening portion in the first direction.

3. The work machine according to claim 2, wherein the insertion portion of the cushioning member is loosely fitted to the end of the coil spring.

4. The work machine according to any one of claims 2 to 3, wherein the insertion portion of the cushioning member includes a large-diameter portion and a small-diameter portion having a smaller diameter than the large-diameter portion.

5. The work machine according to claim 4, wherein the small diameter portion is formed to taper towards the end.

6. The work machine according to any one of claims 1 to 5, wherein the load-receiving portion is provided on the movable portion and is movable in the first direction by receiving the biasing force of the coil spring.

7. The work machine according to any one of claims 1 to 6, wherein the movable part is a plunger that moves the striking part to one side in the first direction by the biasing force of the coil spring.

8. The work machine according to any one of claims 1 to 7, wherein the movable part is a counterweight that moves in the opposite direction to the striking part due to the biasing force of the coil spring.

9. The work machine according to any one of claims 1 to 8, further comprising an elastic member for receiving the movable part that moves under the biasing force of the coil spring.

Images