JP2013208662A - Driving machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving machine capable of increasing a driving force by smoothly making compressed air flow in a piston.SOLUTION: A nail driving machine 1 includes a housing 2, a cylinder 3, a piston 4 movable between a top dead center and a bottom dead center, a head bumper 6 abutted when the piston 4 reaches the top dead center, and a bumper 36 abutted when the piston 4 reaches the bottom dead center. In the piston 4, a piston upper surface 4A facing the head bumper 6 is defined. In the head bumper 6, an abutting surface 61A facing the opposite surface 4A is defined. The piston upper surface 4A and the abutting surface 61A are formed so that a distance between the piston upper surface 4A and the abutting surface 61A near the outer periphery of the piston upper surface is shortest.

Description

  The present invention relates to a driving machine.

  As shown in FIGS. 10 to 11, a conventional nailing machine 101 includes a housing 102 having a pressure accumulating chamber 102a in which compressed air is stored, a cylinder 103, a piston 104 accommodated in the cylinder 103, a piston 104, A driver blade 141 for hitting a nail (not shown) formed integrally, a head bumper 106 provided with an abutting portion 106A capable of abutting on the piston 104, and the pressure accumulating chamber 102a and the cylinder 103 are communicated and blocked. Main valve 131 is mainly included. A fixing hole 161 a that engages with the housing 102 is formed in the head bumper 106.

  In the initial state shown in FIG. 10, the contact portion 106A and the piston 104 are in contact with each other, and the main valve 131 shuts off the cylinder 103 and the pressure accumulating chamber 102a. When the operator pulls a trigger (not shown), as shown in FIG. 11, the main valve 131 moves to connect the inside of the cylinder 103 and the pressure accumulating chamber 102a, and compressed air flows between the head bumper 106 and the piston 104. Get in. As a result, the driver blade 141 moves and a nail (not shown) is driven into the driven material. Such a nailing machine is disclosed in Patent Document 1, for example.

JP 2007-331047 A

  However, in the conventional driving machine 101, since the contact portion 106A protrudes and the fixing hole 161a is formed, the shape change of the head bumper 106 is abrupt. As a result, the compressed air suddenly expands at the location, causing fluid loss. Further, as indicated by an arrow A in FIG. 11, the compressed air that has flowed in was swirled in the vicinity of the contact portion 106A. This vortex became a flow path resistance, and smooth inflow of compressed air from the pressure accumulation chamber 102a into the cylinder 103 was prevented. Due to the occurrence of such a fluid loss, the pressure increase in the cylinder 103 becomes slow, so that the lowering speed of the piston 104 is reduced and the driving force of the nail is reduced. Further, in the state shown in FIG. 11, the distance between the piston 104 and the head bumper 106 is wide at the periphery of the piston 104, narrows toward the contact portion 106 </ b> A, and is widest at the substantially central portion. Then, the compressed air flowing in from the peripheral edge of the piston 104 reaches the widest part through the narrowed part from the part where the distance between the piston 104 and the cylinder 103 is widened. The fluid loss that accompanies was generated.

  Therefore, an object of the present invention is to provide a driving machine that allows compressed air to smoothly flow into a piston to improve driving force.

  To achieve the above object, a housing provided with a pressure accumulating chamber for storing compressed air, a cylinder accommodated in the housing, a main valve for communicating and blocking the cylinder and the pressure accumulating chamber, A piston movable between top dead center and bottom dead center; a first damper contacting the piston when the piston is located at the bottom dead center; and the piston located at the top dead center A second damper having a contact surface defined to contact the piston, the piston having a piston upper surface facing the second damper, the piston upper surface and the corresponding contact surface being A driving machine characterized in that the distance between the upper surface of the piston and the corresponding contact surface in the vicinity of the outer periphery of the upper surface of the piston is the closest.

  According to such a configuration, when the main valve communicates between the cylinder and the pressure accumulating chamber and the compressed air flows into the cylinder, the compressed air flows into the cylinder through the portion where the distance between the piston upper surface and the contact surface is closest. Then, the air gradually expands near the center of the cylinder. Then, compared to the case where the air expands at a stroke at the periphery of the cylinder, the fluid loss associated with the expansion of the compressed air can be suppressed when the air gradually expands toward the center of the cylinder. Thereby, since the pressure rise in a cylinder becomes quick, the descent | fall speed of a piston can improve and driving force can be raised.

  Further, it is preferable that at least one of the upper surface of the piston and the corresponding contact surface is formed such that the distance between the upper surface of the piston and the corresponding contact surface gradually increases as the center axis passes through the center of the piston.

  According to such a configuration, since at least one of the piston upper surface and the contact surface is formed so that the distance between the piston upper surface and the contact surface gradually increases, the main valve communicates between the cylinder and the pressure accumulating chamber. When the compressed air flows into the cylinder, the volume change in the cylinder becomes gradual. Thereby, the fluid loss accompanying compressed air expansion can be suppressed. Furthermore, since the compressed air in the pressure accumulating chamber can be smoothly guided into the cylinder, the generation of vortices accompanying the inflow of compressed air can be suppressed, and the flow path resistance can be minimized. As a result, the pressure rise in the cylinder becomes rapid, so that the lowering speed of the piston can be improved and the driving force can be increased.

  The upper surface of the piston is a curved surface that moves away from the contact surface as it approaches the central axis that passes through the center of the piston, and the contact surface moves away from the upper surface of the piston as it approaches the center axis that passes through the center of the piston. It is preferably a curved surface.

  According to such a configuration, the air gradually expands toward the vicinity of the center of the cylinder, so that the fluid loss associated with the compressed air expansion can be more significantly suppressed. Furthermore, the generation of vortices accompanying inflow of compressed air can be further suppressed.

  Moreover, it is preferable that either one of the upper surface of the piston and the corresponding contact surface is a smooth surface.

  According to such a configuration, since either the upper surface of the piston or the corresponding contact surface is a smooth surface, the work of processing the piston or the second damper becomes unnecessary, and the work process can be reduced.

  The second damper preferably has a mounting surface to be attached to the housing, and the mounting surface is preferably formed with a groove portion recessed inward.

  According to such a configuration, the air in the groove serves as a cushioning material, and the amount of deformation of the second damper increases, so the impact when the piston contacts the second damper can be mitigated. .

  In another aspect of the present invention, a housing provided with a pressure accumulating chamber for storing compressed air, a cylinder accommodated in the housing, a main valve for communicating and blocking the cylinder and the pressure accumulating chamber, A piston movable between top dead center and bottom dead center; a first damper contacting the piston when the piston is located at the bottom dead center; and the piston located at the top dead center A second damper having a contact surface that is in contact with the piston, wherein at least one of the upper surface of the piston and the corresponding contact surface approaches the central axis passing through the center of the piston; A driving machine characterized in that the distance from the contact surface is gradually increased is provided.

  According to such a configuration, the compressed air flowing into the cylinder gradually expands as it approaches the central axis of the piston. Thereby, the fluid loss accompanying compressed air expansion can be suppressed. Then, the pressure rise in the cylinder becomes rapid, so that the lowering speed of the piston is improved and the driving force can be increased.

  The upper surface of the piston is a curved surface that moves away from the contact surface as it approaches the central axis that passes through the center of the piston, and the contact surface moves away from the upper surface of the piston as it approaches the center axis that passes through the center of the piston. It is preferably a curved surface.

  According to such a configuration, the air gradually expands toward the vicinity of the center of the cylinder, so that the fluid loss associated with the compressed air expansion can be more significantly suppressed. Furthermore, the generation of vortices accompanying inflow of compressed air can be further suppressed.

  Moreover, it is preferable that either one of the upper surface of the piston and the corresponding contact surface is a smooth surface.

  According to such a configuration, since either the upper surface of the piston or the corresponding contact surface is a smooth surface, the work of processing the piston or the second damper becomes unnecessary, and the work process can be reduced.

  The second damper preferably has a mounting surface to be attached to the housing, and the mounting surface is preferably formed with a groove portion recessed inward.

  According to such a configuration, the air in the groove serves as a cushioning material, and the amount of deformation of the second damper increases, so the impact when the piston contacts the second damper can be mitigated. .

  According to the present invention, it is possible to provide a driving machine that allows compressed air to flow smoothly into a piston to improve driving force.

The fragmentary sectional view which shows the driving machine by the 1st Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the driving machine by the 1st Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity when the main valve of the driving machine by the 1st Embodiment of this invention is opened. The figure showing the simulation result of the pressure change of the cylinder upper chamber of the driving machine by the 1st Embodiment of this invention, and the conventional driving machine. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the driving machine by the 2nd Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the driving machine by the 3rd Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the driving machine by the modification of the 1st Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the driving machine by the modification of the 2nd Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the driving machine by the modification of the 3rd Embodiment of this invention. The partial expanded sectional view which shows the head bumper vicinity in the initial state of the conventional driving machine. The partial expanded sectional view which shows the head bumper vicinity when the main valve of the conventional driving machine is opened.

  A driving machine according to an embodiment of the present invention will be described with reference to FIGS. A nailing machine 1 which is a driving machine shown in FIG. 1 is a tool for driving a nail which is a stopper, and uses compressed air as its power.

  The nailing machine 1 includes a housing 2, a handle 2 </ b> A located on one side of the housing 2, a cylinder 3 housed in the housing 2, and a space between a top dead center and a bottom dead center housed in the cylinder 3. A movable piston 4, a nose portion 5 connected to the housing 2, and a head bumper 6 capable of contacting the piston 4 are provided. For convenience of explanation, in FIG. 1, the direction in which the handle 2 </ b> A extends from the housing 2 is defined as the rear direction, and the opposite is defined as the front direction. A direction in which the nose portion 5 extends from the housing 2 is defined as a downward direction, and the opposite direction is defined as an upward direction. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction (the front side in FIG. 1 is the left direction, and the reverse is the right direction).

  The housing 2 is provided with a locking portion 2 </ b> C for fixing the head bumper 6. A connecting portion 2B to which an air hose (not shown) connected to a compressor (not shown) is connected is provided at the rear end of the handle 2A. A pressure accumulating chamber 2 a for storing compressed air supplied from the compressor is formed in the handle 2 </ b> A and the housing 2 of the nailing machine 1.

    At the base of the handle 2A, a trigger 12 that is operated by an operator, extends from the lower end of the nose portion 5 to the vicinity of the trigger 12 and is urged from the housing 2 to the nose portion 5 side in the vertical direction along the nose portion 5. A movable push lever 13, a trigger valve portion 14 that is a switching valve that communicates with a main valve 31, which will be described later, and sends and exhausts compressed air, and a plunger 15 that transmits the operation of the trigger 12 to the trigger valve portion 14 are provided. It has been.

  As is well known, the plunger 15 of the trigger valve portion 14 is configured to be pushed up when both the pulling operation of the trigger 12 and the pressing operation of the push lever 13 against the driven material are performed.

  The cylinder 3 has a substantially cylindrical shape, and a return air chamber 3a for storing compressed air for returning the piston 4 to the top dead center is formed on the outer periphery of the lower portion of the cylinder 3. The cylinder 3 is provided with a check valve 3A that can only vent the cylinder 3 to the return air chamber 3a. An air passage 3b that is always open to the return air chamber 3a is formed below the check valve 3A. ing.

  On the outer periphery of the upper part of the cylinder 3, a main valve 31 that communicates and blocks the pressure accumulating chamber 2 a and the inside of the cylinder 3, a main valve spring 32 that biases the main valve 31 upward, and a main valve that houses the main valve spring 32. Chamber 33 is provided. In the initial state (the state shown in FIGS. 1 and 2), the upper end portion of the main valve 31 is in contact with the housing 2, and the inner peripheral portion of the upper end of the main valve 31 is in contact with the head bumper 6. At this time, the pressure accumulation chamber 2 a and the inside of the cylinder 3 are blocked by the main valve 31. When the main valve 31 moves downward, the pressure accumulating chamber 2a communicates with the inside of the cylinder 3 (the main valve 31 is opened). Here, the main valve 31 has a cylindrical shape, and when the main valve 31 is opened, compressed air uniformly flows from the outer periphery of the main valve 31. Below the main valve 31, a valve plate 34 capable of contacting the main valve 31 is provided. An expansion chamber 35 is formed on the outer periphery of the main valve 31, and an exhaust port 35 a communicating with the outside is formed in the expansion chamber 35. The expansion chamber 35 is a chamber for discharging compressed air in a cylinder upper chamber 42 described later to the outside. By causing the compressed air in the cylinder upper chamber 42 to gradually approach the atmospheric pressure via the expansion chamber 35, noise during discharge of the compressed air is reduced. In the initial state, the expansion chamber 35 and the cylinder 3 communicate with each other. A bumper 36 for absorbing surplus energy of the piston 4 is provided at the lower portion of the cylinder 3. The bumper 36 is an elastic body made of urethane or nitrile rubber (NBR). The bumper 36 corresponds to the first bumper of the present invention.

  The piston 4 is made of metal and has a piston upper surface 4A that is a substantially circular surface facing the head bumper 6 and a sliding contact surface 4B that is perpendicular to the piston upper surface 4A and that is in sliding contact with the inner peripheral surface of the cylinder 3. Is prescribed. A driver blade 41 formed integrally with the piston 4 extends downward from the piston 4. A head bumper abutting portion 4C capable of abutting against the head bumper 6 is provided on the periphery of the piston upper surface 4A. The head bumper contact portion 4C is a horizontal surface and is located in the vicinity of the sliding contact surface 4B. Here, “near” refers to a distance from the sliding contact surface 4B toward the central axis C to the length L (FIG. 3). In the present embodiment, the length L is set to 23% of the distance from the sliding surface 4B to the central axis C. In the initial state shown in FIG. 2, the head bumper contact portion 4 </ b> C is in contact with the head bumper 6.

  A central portion (portion other than the head bumper contact portion 4C) of the piston upper surface 4A is provided with a concave portion 4D that is gradually recessed toward the driver blade 41 toward the central axis C of the piston 4. As shown in FIGS. 2 and 3, the recess 4 </ b> D has a substantially U-shaped cross section perpendicular to the central axis C. The deepest part 4D1, which is the most depressed part of the recess 4D, is located on the central axis C. That is, the piston upper surface 4A is formed symmetrically with respect to the central axis 4C.

  The sliding contact surface 4B is a surface orthogonal to the head bumper contact portion 4C, and is provided with an O-ring 4E. As shown in FIG. 3, the piston 4 divides the cylinder 3 into a cylinder upper chamber 42 and a cylinder lower chamber 43 when the piston 4 and the head bumper 6 are separated by a predetermined distance. The O-ring 4E blocks the cylinder upper chamber 42 and the cylinder lower chamber 43.

  The driver blade 41 is provided such that its center is located on the central axis C. A nail (not shown) is driven into the driven material at the lower end of the driver blade 41.

  The nose portion 5 is formed with a guide path 51 that is positioned at the lower end of the housing 2 and guides the driver blade 41 and a nail (not shown). An injection hole 51 a through which a nail (not shown) is injected is defined at the lowermost position of the guide path 51. Behind the nose portion 5 is provided a magazine device 52 that houses a bundle of nails in which a plurality of nails (not shown) are bundled and connected.

  The magazine device 52 is provided with a magazine 53 for filling nails (not shown) and a nail feeder for sequentially feeding nails (not shown) loaded in the magazines 53 into the guide path 51.

  The head bumper 6 has a substantially cylindrical shape, and its center is located on the central axis C. The head bumper 6 includes a contact portion 61 that can contact the piston 4 and a main valve contact portion 62 that can contact the inner peripheral surface of the main valve 31. The contact portion 61 defines a contact surface 61 </ b> A that faces the piston upper surface 4 </ b> A of the piston 4 and a fixed surface 61 </ b> B that is fixed to the inner surface of the housing 2. A fixing hole 61 a is formed in the fixing surface 61 </ b> B, and the fixing hole 61 a is locked with the locking portion 2 </ b> C of the housing 2. As a result, the head bumper 6 is fixed to the housing 2. The head bumper 6 corresponds to the second bumper of the present invention.

  The contact surface 61A has a substantially circular shape, and its area is substantially the same as the piston upper surface 4A. A piston contact portion 61C capable of contacting the piston upper surface 4A is provided at the periphery of the contact surface 61A. The piston contact portion 61C is a horizontal surface and faces the head bumper contact portion 4C. The distance in the radial direction is L, which is the same as that of the head bumper contact portion 4C. In the central portion (portion other than the piston contact portion 61C) of the contact surface 61A, a recess portion 61D that is gradually recessed toward the fixed hole 61a as it goes toward the central axis C is provided. As shown in FIGS. 2 and 3, the recess 61 </ b> D has a substantially U-shaped cross section including the central axis C. The deepest part 61D1 which is the most depressed part of the recessed part 61D is located on the central axis C. That is, the contact surface 61A is formed symmetrically with respect to the center line C. In the present embodiment, the shapes of the piston upper surface 4A and the contact surface 61A are plane symmetric with respect to a plane orthogonal to the central axis C.

  The main valve contact portion 62 has a substantially L-shaped cross section including the central axis C, and is provided on the outer peripheral surface of the contact portion 61 over the entire circumference. As shown in FIG. 2, the main valve abutting portion 62 abuts the main valve 31 to shut off the pressure accumulating chamber 2 a and the cylinder upper chamber 42.

  Next, the operation of the nailing machine 1 will be described.

  In the initial state shown in FIG. 2, the piston 4 is located at the top dead center and is in contact with the head bumper 6. The main valve chamber 33 communicates with the pressure accumulation chamber 2a, and the main valve chamber 33 is filled with compressed air. When the operator pulls the trigger 12 with the push lever 13 pressed against the material to be driven, the main valve chamber 33 becomes atmospheric pressure by the operation of the trigger valve portion 14. The force by which the compressed air stored in the pressure accumulating chamber 2a pushes down the main valve 31 is larger than the force by which the main valve spring 32 pushes the main valve 31 upward, so that the main valve 31 moves downward. Thereby, the compressed air stored in the pressure accumulating chamber 2a flows into the cylinder upper chamber 42, and the state shown in FIG. 2 is changed to the state shown in FIG. At this time, the compressed air in the pressure accumulating chamber 2a smoothly flows into the cylinder upper chamber 42 by the recessed portion 4D and the recessed portion 61D as shown by an arrow B in FIG. Since the recess 4D is provided on the piston upper surface 4A and the recess 61D is provided on the contact surface 61A, the cylinder upper chamber 42 increases in volume toward the central axis C. The compressed air flows into the cylinder upper chamber 42 from the head bumper contact portion 4C and the piston contact portion 61C where the distance between the piston 4 and the head bumper 6 is narrow, and the distance between the piston 4 and the head bumper 6 gradually increases. Since the distance between the piston 4 and the head bumper 6 is between the deepest part 4D1 and the deepest part 61D1 through the recess 61D, the volume change when the compressed air flows into the cylinder upper chamber 42 gradually progresses. Become. As a result, fluid loss accompanying compressed air expansion can be suppressed.

  FIG. 4 is a graph showing the difference in pressure change in the cylinder upper chamber between the present embodiment and the conventional nailing machine 101. The vertical axis represents the pressure change in the cylinder upper chamber, and the horizontal axis represents the elapsed time since the main valve was opened. In FIG. 4, the simulation was performed under the condition that the piston 4 does not move and the pressure of the compressed air to be supplied was 2.3 MPa (high pressure) and the volume of the cylinder upper chamber 42 was 2.3 cm 3. The volume of the cylinder upper chamber 42 is assumed to be about 100 μsec after the main valve 31 is opened. The time from when the main valve 31 is opened until the piston 4 contacts the bumper 36 is about 3 ms. The pressure peak of the cylinder upper chamber of the conventional structure is 400 μs or later and the pressure value is about 2.50 Mpa, whereas the pressure peak of the cylinder upper chamber of the present embodiment is 100 μs and the pressure value is about 3.5 Mpa. It has become. The peak pressure value is higher than the pressure of the compressed air to be supplied. The pressure is the static pressure (compressed air pressure) and the dynamic pressure (pressure due to the flow rate when the compressed air suddenly flows into the cylinder upper chamber 42). ) Is taken into account. In particular, the difference in pressure between 0 and 100 μs is remarkable. This is due to a decrease in fluid resistance when compressed air flows into the cylinder upper chamber in the present embodiment. In the present embodiment, the pressure rise is quicker and the pressure peak value is higher than that of the conventional structure, so that the lowering speed of the piston 4 is faster than that of the conventional structure. Thereby, the driving force of a nail can be improved. In the present embodiment, the driving force can be improved by about 5%. In the present embodiment, the simulation is performed under the above conditions, but such an effect can be obtained regardless of the pressure of the compressed air to be supplied.

  When moving below the main valve 31 and contacting the valve plate 34, the communication between the cylinder lower chamber 43 and the expansion chamber 35 is blocked. When the piston 4 passes through the check valve 3A, a part of the compressed air flowing into the cylinder upper chamber 42 passes through the check valve 3A and flows into the return air chamber 3a. The air in the cylinder lower chamber 43 flows into the return air chamber 3a through the air passage 3b.

  When the piston 4 abuts against the bumper 36, a nail (not shown) is driven into the driven material. When the operator returns the trigger 12, compressed air is again supplied to the main valve chamber 33 by the trigger valve section 14, and the main valve 31 moves upward to shut off the cylinder upper chamber 42 and the pressure accumulation chamber 2a. At the same time, the main valve 31 and the valve plate 34 are separated from each other, and the cylinder upper chamber 42 and the expansion chamber 35 communicate with each other. Thereby, the compressed air in the cylinder upper chamber 42 is discharged to the outside air through the exhaust port 35a. Since the air in the return air chamber 3a cannot pass through the check valve 3A, it flows into the cylinder lower chamber 43 through the air passage 3b. As a result, the piston 4 is returned to the top dead center. At this time, the bumper 6 is cooled by the air flowing around the bumper 6 through the air passage 3b and the air discharged to the outside through the gap 6c.

  According to such a configuration, when the main valve 31 communicates between the cylinder 3 and the pressure accumulating chamber 2a and compressed air flows into the cylinder upper chamber 42, the location where the distance between the piston upper surface 4A and the contact surface 61A is closest ( Since the head bumper contact portion 4C and the piston contact portion 61C pass through each other) and flow into the cylinder upper chamber 42, the compressed air gradually expands toward the central axis C of the cylinder upper chamber 42. Then, when compared with the case where the compressed air rapidly expands immediately after passing through the end portion of the cylinder upper chamber 42, the fluid loss accompanying the expansion of the compressed air is reduced when the compressed air gradually expands toward the central axis C. Can be suppressed. Thereby, since the pressure rise in the cylinder upper chamber 42 becomes rapid, the descending speed of the piston 3 can be improved and the driving force of the nail driver 1 can be increased.

  According to such a configuration, the piston upper surface 4A and the contact surface 61A are formed so that the distance between the piston upper surface 4A and the contact surface 61A gradually increases. When the compressed air flows into the cylinder upper chamber 42 in communication with 2a, the volume change in the cylinder upper chamber 42 becomes gradual. Thereby, the fluid loss accompanying compressed air expansion can be suppressed. Furthermore, since the compressed air in the pressure accumulating chamber 2a can be smoothly guided to the cylinder upper chamber 42, the generation of vortices accompanying the inflow of compressed air can be suppressed, and the flow path resistance can be minimized. As a result, since the pressure rise in the cylinder upper chamber 42 becomes rapid, the descending speed of the piston 3 can be improved and the driving force of the nail driver 1 can be increased.

  According to such a configuration, the piston upper surface 4A, the contact surface 61A, and the plane orthogonal to the central axis C are plane-symmetrical, so that fluid loss due to the expansion of compressed air can be more significantly suppressed. Furthermore, the generation of vortices accompanying inflow of compressed air can be further suppressed.

  Next, a second embodiment of the present invention will be described with reference to FIG. About the same structure as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The piston 4 has a piston upper surface 241A that is a smooth surface. Piston upper surface 241A is horizontal in the state shown in FIG. The piston upper surface 241A is in contact with the piston contact portion 61C at the peripheral edge portion.

  According to such a configuration, in addition to the effects of the first embodiment, the operation of forming the recess 4D as in the first embodiment on the piston upper surface 241A of the piston 4 becomes unnecessary, and the work process is reduced. be able to.

  Next, a third embodiment of the present invention will be described with reference to FIG. About the same structure as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The head bumper 6 has a contact surface 361A that is a smooth surface. The contact surface 361A is horizontal in the state shown in FIG. The contact surface 361A is in contact with the head bumper contact portion 4C at the peripheral portion.

  According to such a configuration, in addition to the effects of the first embodiment, the work of forming the recessed portion 61D as in the first embodiment on the contact surface 361A of the head bumper 6 becomes unnecessary, and the work process is reduced. Can be reduced.

  The driving machine according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims.

  In the embodiment described above, only the fixing hole 61a is formed in the fixing surface 61B of the head bumper 6, but the present invention is not limited to this configuration. For example, as shown in FIG. 7, in the first embodiment, in addition to the fixing hole 61a, a groove portion 461a recessed in an annular shape around the central axis C may be formed. As a result, the air in the groove 461a serves as a cushioning material, and the amount of deformation of the head bumper 6 increases, so that the impact when the piston 4 contacts the head bumper 6 can be mitigated. Further, as shown in FIGS. 8 and 9, grooves 561a and 661a may be formed on the fixing surface 61B of the head bumper 6 of the second and third embodiments, respectively.

  In the embodiment described above, the shapes of the piston upper surface 4A of the piston 4 and the contact surface 61A of the head bumper 6 are such that the distance between the piston 4 increases toward the central axis C in the state of being separated from each other by a predetermined distance as shown in FIG. However, the present invention is not limited to this. For example, even if there is a slight unevenness on either the piston upper surface or the contact surface, if the change is gradual, the generation of vortices can be suppressed.

1 .... Nailer, 2.Housing, 2A ... Handle, 3 .... Cylinder, 4 .... Piston, 4A ..., Piston top, 4B ... Sliding contact surface, 4C ... Head bumper contact part, 4D ...・ Recess, 5 ・ ・ Nose, 6 ・ ・ Head bumper, 12 ・ ・ Trigger, 31 ・ ・ Main valve, 33 ・ ・ Main valve chamber, 34 ・ ・ Valve plate, 35 ・ ・ Bumper, 42 ・ ・ Cylinder upper chamber, 43 .. Cylinder lower chamber 61.

Claims (9)

A housing provided with a pressure accumulation chamber for storing compressed air;
A cylinder housed in the housing;
A main valve for communicating and blocking between the cylinder and the pressure accumulating chamber;
A piston movable between top dead center and bottom dead center in the cylinder;
A first damper that contacts the piston when the piston is located at the bottom dead center;
A second damper having a contact surface that contacts the piston when the piston is located at the top dead center;
The piston has a piston upper surface facing the second damper,
The piston upper surface and the corresponding contact surface are formed so that the distance between the piston upper surface and the corresponding contact surface in the vicinity of the outer periphery of the piston upper surface is closest.   The piston upper surface and the corresponding contact surface are formed such that a distance between the piston upper surface and the corresponding contact surface gradually increases as approaching a central axis passing through the center of the piston. The driving machine described.   The upper surface of the piston is a curved surface that is separated from the corresponding contact surface as it approaches the central axis that passes through the center of the piston, and the corresponding contact surface is a curved surface that is separated from the upper surface of the piston as it approaches the central axis that passes through the center of the piston. The driving machine according to claim 1, wherein:   2. The driving machine according to claim 1, wherein one of the upper surface of the piston and the corresponding contact surface is a smooth surface.   5. The striking device according to claim 1, wherein a mounting surface to be attached to the housing is defined in the second damper, and a groove portion recessed inward is formed on the mounting surface. 6. Embedded machine. A housing provided with a pressure accumulation chamber for storing compressed air;
A cylinder housed in the housing;
A main valve for communicating and blocking between the cylinder and the pressure accumulating chamber;
A piston movable between top dead center and bottom dead center in the cylinder;
A first damper that contacts the piston when the piston is located at the bottom dead center;
A second damper having a contact surface that contacts the piston when the piston is located at the top dead center;
At least one of the upper surface of the piston and the corresponding contact surface is formed such that the distance between the upper surface of the piston and the corresponding contact surface gradually increases as approaching the central axis passing through the center of the piston. Embedded machine.   The upper surface of the piston is a curved surface that is separated from the corresponding contact surface as it approaches the central axis that passes through the center of the piston, and the corresponding contact surface is a curved surface that is separated from the upper surface of the piston as it approaches the central axis that passes through the center of the piston. The driving machine according to claim 6, wherein:   7. The driving machine according to claim 6, wherein one of the upper surface of the piston and the corresponding contact surface is a smooth surface.   9. The striking device according to claim 6, wherein a mounting surface to be attached to the housing is defined in the second damper, and a groove portion recessed inward is formed on the mounting surface. Embedded machine.

Images