JP2010142918A - Driving tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely reduce a shock at a bottom dead point of a piston and prevent rebound even if a high pressure type driving tool, although there is the case where a shock absorbing capability is conventionally insufficient in a damper for absorbing the shock at a top dead point of the piston in the driving tool for striking a driving object by reciprocating the piston by a compressed air. <P>SOLUTION: The driving tool is provided with: a circular truncated cone shaped buffering projection part 10b on the piston 10; and a cylindrical shock absorbing part 31a on a damper 30. The buffering projection part 10b intrudes into a buffering recessed part 31a of a shock absorbing part 31a, and a mouth of a buffering recessed part 31a is elastically deformed in the diameter expanding direction to absorb the shock by bringing a mouth inner peripheral corner part 31b of the buffering recessed part 31a into linearly contact with a tapered surface 10c of the buffering projection part 10b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a driving tool such as a hand-held nailing machine.

For example, a driving tool driven by compressed air is driven in such a manner that a main body with a piston that reciprocates by compressed air and a projecting driver attached to the piston are inserted in a state protruding from the lower part of the main body. A driving portion having a passage, a handle portion extending laterally from the side portion of the main body portion, and a magazine capable of loading a large number of driving tools supplied one by one to the driving portion are provided.
In this type of driving tool, when a trigger-type switch lever provided near the base of the handle is pulled with a fingertip, compressed air is supplied to the cylinder upper chamber of the main body and the piston moves downward. When the piston is moved down by the thrust of the compressed air, the driver moves down in the driving passage, and one driving tool is hit in the middle of the lowering movement, and is driven out from the injection port.
When the pulling operation of the switch lever is released after the driving is completed, the cylinder upper chamber is exhausted, and return air accumulated during piston lowering flows into the cylinder lower chamber. Returning to top dead center automatically completes a series of driving operations.
A damper is attached to the lower part of the cylinder to reduce the impact when the piston reaches the bottom dead center. In addition, a damper is attached to the upper part of the cylinder in order to reduce the impact when the piston is returned to the top dead center. Various ideas have been made for this damper as well. For example, a technique for manufacturing a damper using a material having a small coefficient of restitution is provided, and as disclosed in the following patent document, a protrusion is provided on the upper surface of the piston, while a lower surface of the top dead center damper is provided. There has been provided a technique for absorbing a shock by providing a concave portion and fitting a projection into the concave portion and elastically engaging the piston when the piston reaches top dead center.
No. 6-16671

In recent years, driving tools for hitting driving tools (nails) having a large head (about 10 mm) as a driving tool mainly for fixing roofing materials have been provided. In this type of driving tool, in order to stably drive a large-diameter driving tool, the driver for driving is set to be thicker than usual (about 10 mm) according to the head of the driving tool, and the compression tool is compressed. The working pressure of air is also set to a higher pressure (about 2.26 Mpa) than the normal 0.83 Mpa.
For such a high-pressure type driving tool, a conventional shock absorbing structure using a damper is insufficient. In particular, when the shock absorbing capacity of the top dead center damper is low, a rebound that rebounds back to the striking side (bottom dead center side) occurs due to the reaction force that the piston receives from the damper. The rebounding distance reaches, for example, about 15 mm in some cases.
When the piston rebounds after reaching the top dead center, the driver again moves down in the driving path. In some cases, the next driving tool (the driving tool supplied from the magazine to the driving path for the next driving) The head of is hit. When the next driving tool is the last driving tool of the so-called connecting driving tool, the piston rebound is not held by the connecting member between the rear driving tool and the driving tool in the middle of the connection. If the driver is hit by the driver, there is a problem that the driver falls out of the driving path. Even if the next driving tool is a driving tool in the middle of the connection of the connecting driving tool, if it is struck by piston rebound, it will be displaced in the driving path, which is the so-called jamming (jamming in the driving path). ). This problem of piston rebound is not limited to the high pressure type, and is a problem that occurs not only in the normal pressure type driving tool.
As described above, particularly in a high-pressure type driving tool, it is necessary to prevent or prevent the next driving tool from falling out of the driving path and clogging of the nail in the driving path by suppressing or preventing piston rebound (rebound). Therefore, a higher shock absorbing capacity is required mainly for a damper for top dead center.
An object of the present invention is to provide a driving tool that can be suitably used as a high-pressure type driving tool and has a high impact absorption capability mainly on the top dead center side of the piston.

For this reason, this invention was set as the driving tool of the structure described in each claim of a claim.
According to the driving tool of the first aspect, when the piston reaches the top dead center, the tapered buffer protrusion is fitted into the buffer recess. When the tapered buffer protrusion is fitted into the buffer recess, the corner on the inner peripheral side of the mouth of the buffer recess contacts the tapered surface of the buffer protrusion. As a result of the corner portion on the inner peripheral side of the mouth coming into contact with the tapered surface, the thrust of the piston is concentrated on the corner portion as an external force that causes the mouth portion to bend and deform in the diameter increasing direction. For this reason, since the mouth of the buffer recess is efficiently elastically displaced in the diameter expansion direction, the thrust of the piston and the impact at the top dead center are efficiently absorbed.
In this way, since the mouth of the buffer recess is elastically displaced in a direction perpendicular to or intersecting the piston upward movement direction (diameter expansion direction), the upper surface of the piston is simply brought into contact with the damper as an elastic body. Compared to the configuration in which the damper is elastically deformed (buckled) so as to crush the damper in the upward movement direction of the piston, the buffer recess is greatly elastically displaced in the diameter-expanding direction, and the larger impact of the piston is efficiently performed. Can be absorbed. From this, according to the shock absorbing structure, rebound at the top dead center of the piston can be prevented or reduced, so that the next driving tool can be prevented from being hit, It is possible to prevent the next driving tool from falling out of the driving path, and to prevent misalignment in the driving path to prevent so-called jamming.
In this specification, when the mouth of the buffer recess is elastically displaced in the expanding direction (opening direction), the mouth is pushed and expanded by the entry of the buffer protrusion, and is returned to the original diameter when the buffer protrusion is retracted. I shall say that.
According to the driving tool of the second aspect, when the piston reaches the top dead center, the conical buffer protrusion is fitted into the buffer recess on the damper side. At this time, the corner portion on the inner peripheral side of the mouth of the buffer recess comes into contact with the tapered surface of the buffer protrusion in a line-contact state, and thereby, the thrust of the piston is concentrated on the corner and the mouth of the buffer recess is concentrated. The shock is absorbed by elastically displacing in the diameter-expanding direction. Since the inner peripheral hole of the cylindrical shock absorber provided on the lower surface of the damper is a buffer recess, the mouth can be elastically displaced in the opening direction by appropriately setting the thickness of the shock absorber. Becomes easier.
According to the driving tool of the third aspect, since the damper recess on the damper side is not a tapered hole but a cylindrical hole whose inner diameter does not change, the corner on the inner peripheral side of the mouth is formed on the piston side. The taper surface of the buffer protrusion can be surely contacted with a line.
According to the driving tool of claim 4, the impact (piston thrust) when the piston reaches the top dead center is absorbed by elastically displacing the mouth of the buffer recess in the opening direction, and then the thrust is absorbed. In this state, the upper surface of the piston is elastically pressed against the lower surface of the damper, so that the impact is more reliably absorbed and the piston is stopped without rebounding.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the entire driving tool 1 according to the present embodiment. The driving tool 1 of the present embodiment is characterized by an impact absorbing structure for absorbing an impact when the piston reaches top dead center, and other basic configurations as other driving tools are not particularly required. .
This driving tool 1 is a so-called nailing machine, and includes a main body 2 with a piston 10 built therein, a driving part 3 provided in a state of projecting downward from a lower part of the main body 2, and a side from the side of the main body 2. And a magazine 5 attached in a stretched state between the vicinity of the front end of the handle portion 4 and the driving portion 3.
The piston 10 of the main body 2 is housed in the cylinder 11. An impact driver 12 is attached to the piston 10. The driver 12 extends long downward from the center of the lower surface of the piston 10. The tip of the driver 12 enters the driving passage 3 a of the driving unit 3. A cylindrical head valve 20 is disposed on the cylinder 11. The head valve 20 has a function of opening and closing the cylinder upper chamber 11a with respect to the pressure accumulation chamber 8 to supply and exhaust air. The head valve 20 is supported on the inner side of a substantially cylindrical main body frame 9 provided in the upper part of the main body 2 so as to be movable up and down. Compression springs 21 to 21 are interposed between the main body frame 9 and the head valve 20. The head valves 20 are urged by the compression springs 21 to 21 in the direction of closing the cylinder upper chamber 11a on the lower side in the figure.

An air hose for supplying compressed air as a drive source is connected to the tip of the handle portion 4. In the figure, only the coupler 4a for connecting the air hose is shown. The compressed air supplied through the air hose is once supplied to the pressure accumulating chamber 8 in the handle portion 4.
In the vicinity of the base portion of the handle portion 4, a trigger type switch lever 6 that is pulled by a user with a fingertip and a trigger valve 7 that is actuated thereby are provided. When the trigger valve 7 is activated by pulling the switch lever 6, the upper chamber 20 a side of the head valve 20 is exhausted (released to the atmosphere), and the head valve 20 is moved upward by the compressed air pressure in the pressure accumulating chamber 8 and opened. . When the head valve 20 is opened, the cylinder upper chamber 11a is communicated with the pressure accumulation chamber 8, and compressed air is supplied to the cylinder upper chamber 11a. When the compressed air is supplied to the cylinder upper chamber 11a, the piston 10 moves downward, and the driver 12 moves down in the driving passage 3a, whereby one driving tool is hit, and the tip of the driving portion 3 is moved. It is launched from (injection port).
A driving tool is supplied to the driving unit 3 one by one in conjunction with the driving operation of the main body unit 2. The magazine 5 is loaded with a connected driving tool in which a number of driving tools are connected in parallel in a wound state. When the distal end side of the connecting driving tool is pitch-fed in conjunction with the driving operation of the main body 2, the driving tools are supplied one by one into the driving passage 3a. In the figure, the driving tool and the connecting driving tool are not visible.

A shock absorbing damper 22 at the bottom dead center of the piston is attached to the lower portion of the cylinder 11. When the piston 10 reaches the bottom dead center by the driving operation, the piston 10 abuts against the damper 22 and is elastically deformed, so that the impact is alleviated.
On the other hand, a shock absorbing damper 30 at the top dead center of the piston is attached to the center of the lower surface of the main body frame 9. When the piston 10 is returned to the top dead center upon completion of the driving operation, the impact of the piston 10 is abutted against the damper 30 to reduce the impact. The present embodiment is characterized by the shock absorbing structure of the piston 10 with respect to the top dead center damper 30. A configuration around the top dead center damper 30 is shown in FIG.
A circular pedestal 10 a is integrally provided on the upper surface of the piston 10. A truncated cone-shaped buffering protrusion 10b is integrally provided on the upper surface of the pedestal 10a. The buffer protrusion 10b has a tapered shape in a direction in which the upper side (tip side) becomes smaller in diameter.

On the other hand, at the center of the lower surface of the damper 30, a cylindrical buffer absorbing portion 31 is integrally provided. The damper 30 and the buffer absorbing portion 31 are integrally formed of a material having moderate elasticity. The inner peripheral hole of the buffer absorbing portion 31 is a buffer recess 31a. The buffer recess 31a has a cylindrical shape whose diameter does not change, and the inner diameter d is appropriately set. The inner diameter d of the buffer recess 31a is set to be larger than the minimum diameter of the buffer protrusion 10b on the piston 10 side and smaller than the maximum diameter.
For this reason, as shown in the drawing, immediately before the piston 10 reaches its top dead center, the tip of the buffer projection 10b enters the buffer recess 31a, and then the mouth inner peripheral corner 31b of the buffer recess 31a is first loosened. It contacts the tapered surface 10c of the collision part 10b. Moreover, the inner peripheral corner portion 31b abuts against the tapered surface 10c over the entire circumference in a line-contact state. For this reason, as shown in FIG. 3, the thrust P of the piston 10 causes the buffer absorbing portion 31 to bend and deform (bend) in the diameter increasing direction uniformly and intensively on the inner peripheral corner portion 31 b of the mouth. ) Acts as an external force (bending force M). The thickness t of the buffer absorbing portion 31 is set so that the bending deformation is appropriately performed. Thus, since it is the structure which does not compress-deform in the direction (buckling direction) which crushes the impact-absorbing part 31, but bend-deforms in the diameter-expanding direction, the impact at the time of reaching the top dead center of the piston 10 is more. Therefore, it is possible to absorb effectively, so that the repulsion of the damper 30 with respect to the piston 10 can be reduced. Since the repulsion of the damper 30 can be reduced to prevent the piston 10 from rebounding or greatly reduced as compared with the prior art, it is possible to prevent the next driving tool from being hit, and thereby the driving path for the next driving tool. It is possible to prevent the jamming from occurring by preventing the slipping out from the inside and the displacement in the driving path.
The piston 10 moves upward while spreading the buffer absorber 31 from its mouth by causing the buffer protrusion 10b to enter the buffer recess 31a, and finally the upper surface of the pedestal 10a is applied to the lower surface of the shock absorber 31. It touches and it reaches the top dead center. The impact (thrust P) of the piston 10 is also absorbed by bringing the upper surface of the pedestal portion 10a into contact with the lower surface of the impact absorbing portion 31 and thereby compressing the impact absorbing portion 31 in the buckling direction.

According to the driving tool 1 of the present embodiment configured as described above, at the stage where the piston 10 is returned to the top dead center, the buffer protrusion 10b first enters the buffer recess 31a and the buffer surface enters the taper surface 10c. The mouth inner peripheral corner portion 31b of the recess 31a is brought into contact, and in this contact state, the estimated amount P of the piston 10 acts as a bending force M that pushes the mouth in the diameter increasing direction. As described above, since the shock is absorbed by bending deformation instead of buckling (crushing) the mouth of the buffer recess 31a of the shock absorbing portion 31, the impact of the piston 10 is absorbed more efficiently. Thus, the rebound caused by the repulsive force of the damper 40 of the piston 10 can be prevented or reduced. As a result, it is possible to prevent the next driving tool from being hit and to prevent it from falling out of the driving path, and to prevent displacement in the driving path and to prevent the occurrence of jamming.
Moreover, since the impact at the top dead center of the piston 10 can be reduced more efficiently than before, the shock absorbing structure can be suitably applied to the high-pressure type driving tool 1 in particular.
Here, as shown in FIG. 5, when considering a conventionally known shock absorbing structure that does not include the buffer protrusion 10b and the buffer recess 31a illustrated above, in this case, the piston 50 reaches the top dead center and the lower surface of the damper 60. , The thrust of the piston P acts on the lower surface of the damper 60 as it is at right angles and acts as an external force (buckling force Z) for buckling (crushing) the damper 60. For this reason, as illustrated above, the repulsive force received from the damper 60 is greater than when the mouth of the buffer recess 31a is bent and deformed in the diameter increasing direction, and as a result, the rebound of the piston 50 increases.

  From the above, in the illustrated embodiment, the piston 10 has been illustrated as a configuration in which the inner peripheral corner portion 31b of the buffer recess 31a is brought into contact with the tapered surface 10c of the buffer projection 10b when reaching the top dead center. Here, the term “per line contact” means that the mouth inner peripheral corner portion 31b is a so-called pin angle or an R surface, so that the mouth inner peripheral corner portion 31b is a so-called C-plane and is a so-called C surface. This also includes the case of contact with a certain width. In short, as shown in FIG. 5, most of the thrust P of the piston 50 that moves upward does not act as a buckling force Z against the damper 50, and a part or most of the thrust P has the buffer recess 31 a. The above-described effects can be obtained by adopting a configuration that acts as a bending force M that displaces the mouth in the diameter increasing direction.

Various modifications can be made to the embodiment described above. For example, although the cylindrical buffer-shaped recess 31a whose diameter does not change is illustrated, it may be a truncated cone-shaped buffer recess 41a whose diameter changes as shown in FIG. The buffer recess 41a according to the second embodiment is provided on the inner peripheral side of the shock absorbing portion 41 provided on the lower surface of the top dead center damper 40, like the buffer recess 31a according to the first embodiment. The inner peripheral surface of the buffer recess 41a has a tapered surface inclined in a direction in which the mouth side has a large diameter and the bottom side has a small diameter. From the mouth side to the bottom side, the diameter of the buffer recess 41a is continuously reduced without increasing in the middle.
The shock-absorbing protrusion 10b on the piston 10 side has a truncated cone shape that is inclined in the direction of a smaller diameter toward the distal end side as in the first embodiment. However, the inclination angle of the tapered surface of the buffer protrusion 10b with respect to the upper surface of the pedestal portion 10a is smaller than the tapered surface of the buffer recess 41a (the difference between the large diameter and the small diameter is large). For this reason, when the buffer protrusion 10 enters the buffer recess 41a, the mouth inner peripheral corner 41b of the buffer recess 41a surely contacts the tapered surface of the buffer protrusion 10b. For this reason, also in the second embodiment, the bending force M in the diameter increasing direction is reliably applied to the mouth of the buffer recess 41a.
Even in the shock absorbing structure according to the second embodiment, when the piston 10 is returned to the top dead center, the buffer protrusion 10b first enters the buffer recess 41a, and the tapered surface 10c enters the mouth of the buffer recess 41a. The circumferential corner portion 41b is brought into contact, and in this contact state, the thrust of the piston 10 acts on the mouth as a bending force M in the diameter increasing direction. For this reason, the impact when the piston 10 reaches the top dead center is efficiently absorbed by elastically displacing the opening of the buffer recess 41a in the opening direction, thereby preventing the piston 10 from rebounding due to the repulsive force of the damper 40 or It can be greatly reduced to avoid hitting the next driving tool to prevent dropping out of the driving path, and to prevent misalignment in the driving path and so-called jamming can be prevented. .
In addition, the configuration in which the piston is provided with a buffering projection and the damper is provided with a buffering recess, but conversely, the buffering recess is provided on the upper surface of the piston, and the truncated cone-shaped buffering projection is provided on the lower surface of the damper. Also good. Even in the latter case, when the piston is returned to the top dead center, the damper-side buffer protrusion enters the piston-side buffer recess, and the corner on the inner periphery of the mouth is the tapered surface of the buffer protrusion. , The mouth of the buffer recess can be elastically displaced in the diameter-expanding direction to absorb the shock efficiently.
Needless to say, the various types of impact absorbing structures exemplified above are applicable not only to high-pressure type driving tools but also to normal-pressure type (for example, 0.83 MPa) driving tools.

It is the longitudinal cross-sectional view of the whole driving tool provided with the impact-absorbing structure of 1st Embodiment. It is a figure which shows the impact-absorbing structure of 1st Embodiment, and is a longitudinal cross-sectional view around a damper. This figure shows a state in which the damper inner peripheral corner portion on the damper side is in contact with the tapered surface of the buffer protrusion. It is a side view of the impact absorption structure of 1st Embodiment. This figure shows a state in which the mouth of the buffer recess is pushed out by the buffer protrusion. It is a side view of the shock absorption structure of 2nd Embodiment. This figure shows a state in which the mouth of the buffer recess is pushed out by the buffer protrusion. It is a conventional shock absorbing structure, and is a side view of a top dead center damper and a piston.

Explanation of symbols

1 ... Driving tool (high pressure pneumatic nailing machine)
DESCRIPTION OF SYMBOLS 2 ... Main-body part 3 ... Drive-in part, 3a ... Drive-in path 4 ... Handle part, 4a ... Coupler 5 ... Magazine 8 ... Accumulation chamber 9 ... Main body frame 10 ... Piston, 10a ... Base part, 10b ... Buffering protrusion, 10c ... Taper Surface 11 ... Cylinder, 11a ... Cylinder upper chamber 12 ... Driver 20 ... Head valve, 20a ... Upper chamber 21 ... Compression spring 22 ... Damper (for bottom dead center)
30 ... Damper (for top dead center)
31 ... Shock absorbing portion, 31a ... Buffer recess, 31b ... Inner peripheral corner t ... Shock absorber thickness d ... Buffer recess diameter M ... Bending force P against buffer recess mouth ... Thrust Z when piston moves up ... Buckling force (crushing force) against the damper
40 ... Damper (second embodiment)
41 ... Shock absorbing portion, 41a ... Buffer recess 50 ... Piston (conventional)
60 ... Damper (conventional)

Claims (4)

A driving tool including a piston that reciprocates in a cylinder built in a main body by compressed air, and a damper for absorbing an impact at the top dead center of the piston, the upper surface of the piston and the lower surface of the damper One of the two is provided with a tapered buffer projection, the other is provided with a buffer recess into which the buffer projection fits, and the corner on the inner peripheral side of the buffer recess is brought into contact with the tapered surface of the buffer projection. A driving tool configured to absorb the impact by elastically displacing the mouth of the buffer recess in the diameter expanding direction. 2. The driving tool according to claim 1, wherein the buffer protrusion is provided on a top surface of the piston in a truncated cone shape having a smaller diameter toward an upper side, and the buffer recess protrudes in a cylindrical shape on the lower surface of the damper. A driving tool used as the inner peripheral hole of the provided shock absorber. 3. The driving tool according to claim 2, wherein an inner peripheral hole of the shock absorbing portion has a cylindrical body shape whose inner diameter does not change. 2. The driving tool according to claim 1, wherein the upper surface of the piston is elastically pressed against the lower surface of the damper and the shock is absorbed while the mouth of the buffer recess is elastically displaced in the opening direction.

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