JP4984487B2 - Driving force adjusting mechanism of pneumatic screw driving machine - Google Patents

Description

  The present invention relates to an adjusting mechanism for adjusting a driving force of a driver bit for driving in a pneumatic screw driving machine.

  Generally, a pneumatic screw driving machine is designed to lightly drive a driving screw into a material to be driven and then tighten it firmly. According to such driving and screw tightening processes, each of the driving screws hits the driving screw. A mechanism and a screw tightening mechanism for rotating the driving screw are provided. The striking mechanism is configured such that a driver bit is integrally coupled to a striking piston slidably accommodated in a striking cylinder, a main valve is actuated by a trigger operation, and an air chamber for storing compressed air is provided with respect to the striking cylinder. It is opened and closed, and compressed air is supplied to the striking cylinder to drive the striking piston. Conventionally, the supply amount of compressed air is always constant, and therefore the striking force by the striking piston is always constant. At the time of driving, it is necessary that the tip of the driving screw penetrates the upper material and is driven to the middle of the base.

  However, for example, even if the upper material constituting the material to be driven is a gypsum board, there are cases where the base is a wooden board and a steel sheet. Since the wooden board is softer than the steel sheet, the energy for driving the driving screw through the upper member and driving it halfway through the wooden board may be smaller than that of the steel sheet. However, it is not sufficient to pierce the steel plate with the tip of the driving screw with this driving energy. On the other hand, when the driving energy is matched to the steel plate, if the driving screw is driven into the base of the wooden board with this driving energy, the driving screw may penetrate the wooden board or the displacement due to the reaction force of the screw driving machine. There is an inconvenience that the tip of the driver bit cannot be engaged with the head groove of the driving screw and screw tightening failure occurs.

Therefore, in order to improve the above inconvenience, an air supply port for supplying compressed air from the air chamber into the striking cylinder is formed in two stages, and a valve body for selectively opening and closing these air supply ports is provided. A technique is known in which the stroke is changed by operating from the outside, the pipe area is switched by this stroke difference, and the amount of air supplied to the striking cylinder can be adjusted.
Japanese Patent No. 3520443

  However, due to the deformation of the valve stopper part that suppresses the stroke of the valve body, even if the driving force is set to `` weak '', a phenomenon that it switches to `` strong '' occurs, the overall height of the tool becomes high, There was a problem that the number of parts increased.

  The present invention solves the above-mentioned problems, can adjust the driving force to ensure that the driving depth of the driving screw against the driven material can be made appropriate, and can further reduce the overall height of the tool, It is an object of the present invention to provide a driving force adjusting mechanism for a pneumatic screw driving machine that can reduce the number of parts.

In order to solve the above-described problem, the invention according to claim 1 is directed to supplying compressed air stored in an air chamber provided in a tool body from an annular main valve provided in an upper portion of a hitting cylinder to an internal hitting piston. A striking mechanism for driving the driver bit integrally coupled downward and a screw tightening mechanism for rotating the driver bit by an air motor. The driver bit strikes the driving screw by the striking mechanism to strike the workpiece. On the other hand, in the pneumatic screw driving machine in which the screw screw is tightened by the screw tightening mechanism after the head of the driving screw is floated, the upper part is squeezed inside the main valve. A valve housing having a through hole with an upper portion opened to the air chamber is provided, and the lower end protrudes into the valve housing. A shaft-shaped valve main body is arranged so as to be movable up and down. Inside the valve main body, a lower surface opening that opens to the striking cylinder and a side opening that opens to the air chamber through a through hole of the valve housing, When the valve main body moves up and down, the outer peripheral surface below the side opening is brought into contact with or separated from the inner peripheral surface of the valve housing, and the valve main body is moved to the tool main body. It is provided so that it can be moved up and down by an external operating means, and when the valve body moves upward , compressed air in the air chamber is sent from the through hole of the valve housing to the lower surface of the air supply passage through the side opening of the valve body. While being supplied into the impact cylinder from the opening, the compressed air in the air chamber is supplied from the through hole of the valve housing when the valve body is moved downward. The gap between the outer peripheral surface of the bulging portion of the lower portion of the valve body and the inner peripheral surface of the valve housing is supplied from the through hole to the impact cylinder through the side surface opening of the main body and from the lower surface opening of the air supply passage. It supplies to a striking cylinder through this .

  According to a second aspect of the present invention, the operation means is provided with an operation lever provided with stepped engagement grooves formed in upper and lower steps formed horizontally on the upper part of the tool body so as to be movable in the horizontal direction. The engagement portion formed at the upper end of the valve body is engaged with the stepped engagement groove.

  The invention according to claim 3 is characterized in that, in the operation lever, one end thereof is pivotally attached to the tool main body, and the other end is swingable left and right.

  According to the first aspect of the invention, when a large driving force is not required, the valve body is moved upward by the operating means, and the outer peripheral surface below the side opening is brought into contact with the inner peripheral surface of the valve housing. Let Thereby, since compressed air is supplied only from the lower surface opening part of an air supply path, the driving force is comparatively small. Accordingly, the driving screw is driven to an appropriate driving depth on a soft base such as a wooden board. On the other hand, when a large driving force is required, the valve body is moved downward by the operating means, and the outer peripheral surface below the side opening is separated from the inner peripheral surface of the valve housing. As a result, the compressed air is supplied into the striking cylinder through the gap between the outer peripheral surface of the bulging portion of the valve body and the inner peripheral surface of the valve housing together with the lower surface opening of the air supply passage. Power is obtained. Therefore, the driving screw can be driven to an appropriate driving depth even on a hard base such as a steel plate.

  In this way, by switching the switching valve, the gap between the outer peripheral surface of the valve body and the inner peripheral surface of the valve housing is selectively opened and closed so that the driving force by the driver bit corresponds to the type of the driven material. It can be adjusted and the driving depth of the driving screw can always be adjusted appropriately.

  Moreover, since the switching valve is disposed inside the annular main valve, the height of the entire tool can be kept low.

  According to the invention which concerns on Claim 2, the operation means of the switching valve can move an operation lever provided with the step-shaped engagement groove formed in the upper and lower step shape horizontally formed in the upper part of a tool main body to a horizontal direction Since the engaging portion formed at the upper end of the valve body is engaged with the stepped engaging groove, the valve body is moved up and down by converting the horizontal movement of the operating lever. Therefore, the switching is not performed without permission, and the driving depth of the driving screw can be surely made appropriate.

  Furthermore, since the valve body is directly switched by the operation lever, the number of parts can be reduced.

  The invention according to claim 3 is easy to operate because the operation lever has one end pivotally attached to the tool body and the other end swingable left and right.

  FIGS. 1 and 2 (a) and 2 (b) show the main part of the upper surface of the screw driving machine and the cross section on the line XX of FIG. 1, respectively. And a screw tightening mechanism. The striking mechanism has a striking cylinder 1, a striking piston 2 slidably provided in the striking cylinder 1, and a driver bit 3 integrally coupled to the striking piston 2, and pulls a trigger (not shown). The main valve 4 is opened and compressed air is supplied into the striking cylinder 1 from an air chamber (connected to an air supply source) 5 for storing the compressed air, and the driver bit 3 is driven and operated. The screw tightening mechanism (not shown) is for screwing the driver bit 3 with power from an air motor or the like. The main valve 4 is opened and operated almost simultaneously with the start of the operation of the impact mechanism. A part of the compressed air flowing in from is supplied to an air motor and rotates the driver bit 3 around its axis, thereby tightening a driving screw driven by the driver bit 3.

  The driver bit 3 hits the driving screw by the driving mechanism and drives the driving screw so that the head of the driving screw floats against the material to be driven, and then the driving screw is tightened by the screw tightening mechanism. Such a striking mechanism and a screw tightening mechanism are known mechanisms as known from, for example, Japanese Patent Application Laid-Open No. 2000-79691, Japanese Patent Application Laid-Open No. 9-141571.

  A main valve 4 is disposed around the cylinder head portion of the striking cylinder 1. The main valve 4 is formed in an annular shape as shown in FIG. 4, and its lower end surface is provided to be engageable with the upper end of the inner wall of the air chamber 5 by sliding in the vertical direction. Compressed air is supplied, and the main valve 4 is lowered by the pressure of the compressed air and the spring 7 so that the lower end of the main valve 4 is brought into contact with the upper end of the inner wall of the air chamber 5, thereby closing the air chamber 5 with respect to the striking cylinder 1. ing. On the other hand, by operating the trigger valve (not shown) by pulling the trigger to discharge the compressed air in the valve upper chamber 6, the main valve 4 is moved up as shown in FIG. The lower end is separated from the upper end of the inner wall of the air chamber 5, and the air chamber 5 is opened to the striking cylinder 1.

  A driving force adjusting mechanism is provided in the inner space of the main valve 4. The driving force adjusting mechanism includes a switching valve 8 and an operating means.

  As shown in FIGS. 2A and 4, the switching valve 8 includes a valve housing 9 having a cylindrical shape with a conical lower portion, and a shaft that is inserted into the valve housing 9 so as to be vertically movable. The valve housing 9 is throttled at the upper part, and a through hole 12 communicating with the air chamber 5 is formed at the upper part of the throttle part 11. A piston stop 13 is attached to the lower portion of the valve housing 9 to hold the striking piston 2 in that state when it reaches top dead center.

  A valve body 10 is disposed inside the valve housing 9 so as to be movable up and down. A shaft-like portion 14 is formed at the upper portion of the valve body 10 and a bulging portion 15 is formed at the lower end. An air supply path 16 is formed in the valve body 10. The upper portion of the air supply path 16 is open to the side surface of the base portion of the bulging protrusion 15. Further, the lower portion of the air supply path 16 is open to the lower surface. The side opening 17 opens to the air chamber 5 side through the through-hole 12, and the lower surface opening 18 opens to the striking cylinder 1 side. An O-ring 20 is attached to the outer peripheral surface below the side opening 17.

  Next, the valve body 10 is provided so that it can be moved up and down by operating means outside the tool body. That is, as shown in FIGS. 1, 3 (a) and 4, the operating means includes an operating lever provided with two upper and lower stepped engaging grooves 21 formed horizontally on the upper part of the tool body A. 22, the operation lever 22 is provided so as to be movable in the horizontal direction, and an operating shaft 34 formed at the upper end of the valve body 10 is engaged with the stepped engagement groove 21.

  The operation lever 22 is formed by integrally connecting an upper lever 22a and a lower lever 22b which are divided into upper and lower portions, and a stepped engagement groove 21 formed in the width direction by arranging the two levers is arranged at the center. Has been. The step between the upper engaging groove 21 a and the lower engaging groove 21 b of the stepped engaging groove 21 is an inclined surface 24. A through-opening 25 is opened in the center of the lower engaging groove 21b in the continuous direction of the stepped engaging groove 21. The operation lever 22 is disposed on the upper surface of the upper wall 27 of the cylinder cap 26 disposed above the striking cylinder 1, one end of which is pivotally attached to a support shaft 28 provided on the upper wall 27, and the other end. A grip portion 29 is formed, and this grip portion 29 protrudes to the outside from an opening 32 (see FIG. 1) of an upper surface cover 31 fixed by a bolt 30 above the upper wall 27, whereby the operation lever 22 is Attached so as to be swingable in the left-right direction along the upper surface of the horizontal upper wall 27.

  On the other hand, the shaft-like portion 14 of the valve body 10 of the switching valve 8 passes through the upper wall 27 of the cylinder cap 26 through the upper end of the valve housing 9, and further passes through the through hole 25 of the lower lever. It protrudes at the top. And the operating shaft 34 is attached to the upper end in the direction orthogonal to the axial center of the shaft-shaped part 14 as an upper end engaging part. The operation shaft 34 is disposed so as to engage with the stepped engagement groove 21 of the operation lever 22.

Next, an operation mode of the driving force adjusting mechanism having the above configuration will be described. First, when the base material to be driven is a soft material such as a wood board and does not require a large driving force, the operation shaft 34 is rotated by rotating the operation lever 22 as shown in FIG. It operates so that it may engage with the upper stage engaging groove 21a of the shape engaging groove 21. FIG. Since the valve main body 10 of the switching valve 8 moves upward, as shown in FIG. 2A, the O-ring 20 on the outer peripheral surface below the side opening 17 of the valve main body 10 is connected to the inner periphery of the valve housing 9. Contact the surface. Accordingly, when the main valve 4 is opened and operated as shown in FIG. 2 (b) by pulling a trigger to start the screw driving machine, the compressed air in the air chamber 5 is supplied to the inside of the main valve 4, and the valve The air is supplied into the striking cylinder 1 from the through hole 12 of the housing 9 through the side surface opening 17 of the valve body 10 and from the lower surface opening 18 of the air supply path 16. The striking piston 2 is driven as described above by the pressure of the compressed air, and a driving screw is driven by the driver bit 3. Thus, since the compressed air is supplied only from the lower surface opening 18 of the air supply path , the driving force is relatively small. Therefore, the driving screw is driven to an appropriate driving depth in the base wood board. Thereafter, the driving screw is fastened to the wooden board by the screw tightening mechanism.

On the other hand, when the base of the material to be driven requires a large driving force like a steel plate, the operation lever 34 is rotated as shown in FIG. The adjustment operation is performed so as to engage with the lower engagement groove 21b of the 21. Since the valve main body 10 of the switching valve 8 moves downward, as shown in FIG. 5A, the O-ring 20 on the outer peripheral surface below the side opening 17 of the valve main body 10 is the inner periphery of the valve housing 9. Separate from the surface. As a result, when the trigger is pulled and the main valve 4 is opened to operate, the compressed air in the air chamber 5 passes through the through hole 12 of the valve housing 9 as shown in FIG. Is supplied into the striking cylinder 1 from the lower surface opening 18 of the air supply passage 16 through the side opening 17. At the same time, the air that has passed through the through hole 12 of the valve housing 9 passes through the gap 35 between the outer peripheral surface of the bulging projection 15 of the valve body 10 and the inner peripheral surface of the valve housing 9, and another air supply path 16 a. Since it is supplied into the striking cylinder 1 from above, a large driving force is obtained. Therefore, the driving screw can be driven to an appropriate driving depth with respect to the underlying steel plate.

  When the main valve 4 is closed by the trigger as shown in FIGS. 2A and 5A, the air chamber 5 is closed with respect to the striking cylinder 1 and the exhaust passage 36 (see FIG. 2). Is opened, the striking piston 2 moves upward, and the compressed air supplied into the striking cylinder 1 is discharged to the outside from the exhaust passage 36. At this time, the elastic member 38 extends from the exhaust opening 37 at the top of the striking cylinder and is exhausted to the outside.

  As described above, by the switching operation of the switching valve 8, the gap between the outer peripheral surface of the valve body 10 and the inner peripheral surface of the valve housing 9 is selectively opened and closed, and the driving force by the driver bit 3 is applied to the driven material. It can be adjusted according to the type. Moreover, it is possible to always properly adjust the stepping engagement groove 21 and the driving depth of the driving screw with respect to the driven material.

  Further, since the vertical movement of the valve body 10 is performed by converting the horizontal swinging motion of the operation lever 22, the operation is easy and the switching is not performed on its own, and the driving depth of the driving screw is increased. It can be ensured properly.

  Furthermore, since the switching valve is disposed inside the annular main valve, the height of the entire tool can be kept low.

  Furthermore, since the valve body 10 is directly switched by the operation lever 22, the number of parts can be reduced.

In the embodiment of the driving force adjusting mechanism described above, the operation lever 22 is provided with the upper and lower two-stage stepped engagement grooves 21, but the upper, middle, and lower three-stage engagement grooves are provided on the operation lever. You may comprise so that it may be provided. According to this, as shown in FIG. 6A, in the same manner as described above, the operating lever is rotated so that the operating shaft of the valve body 10 of the switching valve becomes the upper engaging groove of the stepped engaging groove. When operated so as to engage, the compressed air in the air chamber at the time of start-up passes from the through hole 12 of the valve housing 9 to the side opening 17 of the valve body 10 and into the striking cylinder 1 from the lower surface opening 18 of the air supply path 16. Supplied. Since the compressed air is supplied only from the lower surface opening 18 of the air supply path , the driving force is relatively small.

  Next, when the operation lever is operated to engage the operating shaft of the valve body 10 with the middle engaging groove, the compressed air in the air chamber penetrates the valve housing 9 as shown in FIG. The hole 12 is supplied into the striking cylinder from the lower surface opening 18 of the air supply passage 16 through the side surface opening 17 of the valve body 10, and the outer peripheral surface of the bulging protrusion 15 of the valve body 10 and the inner periphery of the valve housing 9. Since it is supplied into the striking cylinder from the air supply path 16a passing through the gap 35 between the surface, a large driving force can be obtained.

  Further, when the operation lever is operated so as to engage the operating shaft of the valve main body 10 with the lower engaging groove, the compressed air in the air chamber at the time of start-up is as shown in FIG. It is supplied into the striking cylinder 1 from the through hole 12 through the side opening 17 of the valve body 10, the lower surface opening 18 of the air supply path 16, and another air supply path 16 b passing through the gap 35. Since the air supply path 16b is larger than the air supply path 16a in the upper figure (b), a larger driving force can be obtained.

It is a top view of the principal part of a screw driving machine. (A) (b) is sectional drawing which showed the principal part on the XX line | wire of FIG. 1 in the state which closed the main valve, and the open state, respectively. (A) and (b) are cross-sectional views showing the cross-section of the main part on the line BB in FIG. 1 by switching the engagement mode between the operating shaft and the engagement groove when a large driving force is not required. . It is a disassembled perspective view of a driving | running | working adjustment mechanism. (A) (b) is sectional drawing which switched the engagement aspect of an operating shaft and an engagement groove | channel, and showed the principal part cross section on the YY line | wire of FIG. 1 when a big driving force is each required. The (A) (b) (c) is sectional drawing of the principal part which shows the operating state of the switching valve in another embodiment.

DESCRIPTION OF SYMBOLS 1 Stroke cylinder 2 Stroke piston 5 Air chamber 9 Valve housing 10 Valve main body 16 Air supply path 21 Stepped engagement groove 22 Operation lever 23 Engagement part (operation shaft)

Claims (3)

A striking mechanism for supplying compressed air stored in an air chamber provided in the tool body from an annular main valve provided at the top of the striking cylinder and driving a driver bit integrally coupled to a striking piston inside the striking piston; A screw tightening mechanism for rotating the driver bit by an air motor, and after the driver bit strikes the driving screw by the striking mechanism and the head of the driving screw is lifted to such an extent that the head of the driving screw floats. In a pneumatic screw driving machine that tightens the driving screw with a screw tightening mechanism,
Provided inside the main valve is a valve housing having an upper portion that is throttled and the upper portion of the throttle portion having a through hole that opens into the air chamber. A shaft-like valve having a lower end projecting into the valve housing An air supply path having a main body arranged so as to be movable up and down and having a lower surface opening that opens to the impact cylinder and a side opening that opens to an air chamber through a through hole of the valve housing. Form the
When the valve body moves up and down, the outer peripheral surface below the side opening is brought into contact with or separated from the inner peripheral surface of the valve housing, and
The valve body is provided so that it can be moved up and down by operating means outside the tool body ,
When the valve body moves upward, compressed air in the air chamber is supplied from the through hole of the valve housing to the impact cylinder from the lower surface opening of the air supply path through the side opening of the valve body.
When the valve main body is moved downward, compressed air in the air chamber is supplied from the through hole of the valve housing through the side opening of the valve main body to the striking cylinder through the lower surface opening of the air supply passage. From the outer peripheral surface of the bulging protrusion at the lower part of the valve body and the inner peripheral surface of the valve housing to be supplied into the striking cylinder. mechanism.   The operating means is provided at the upper end of the valve body with an operating lever provided with a stepped engaging groove formed in an upper and lower step shape formed horizontally on the upper part of the tool body so as to be movable in the horizontal direction. 2. The driving force adjusting mechanism for a pneumatic screw driving machine according to claim 1, wherein the engaging portion is engaged with the stepped engaging groove.   3. The driving force adjustment of the pneumatic screw driving machine according to claim 2, wherein one end of the operating lever is pivotally attached to the tool body and the other end can be swung left and right. mechanism.

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