JP2008114343A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool improved in cutting performance by reducing power working in a direction separate from a material to be cut on a blade as much as possible. <P>SOLUTION: A second shaft 9 is rotated since rotation of an electric motor is transmitted. The second shaft 9 is provided with an eccentric shaft. A base end part of a reciprocation plate 18 is connected to the eccentric shaft via a ball bearing. A virtual extension line of an axial center of a plunger 20 and a virtual extension line of an axial center of a drive rotary shaft 9A form a positional relation to cross at a prescribed angle β. When a locus drawn by oscillation of a spherical part 18b of the reciprocation plate 18 is virtually bisected by the spherical part 18b when a direction for connecting a base end part and the spherical part 18b of the reciprocation plate 18 and a direction of the axial center of the plunger 20 form a positional relation to be perpendicular to each other, the prescribed angle β is taken as a value of an angle so that one length of the bisected locus becomes three times as long as the other length or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric tool provided with a motion conversion means for converting a rotary motion into a reciprocating motion of a reciprocating member.

  There is a saver saw as a reciprocating type cutting tool (electric tool) driven by an electric motor. In a saver saw, generally, a reciprocating shaft (hereinafter referred to as a plunger) equipped with a linear saw blade (hereinafter referred to as a blade) is driven to reciprocate, and cutting is performed by the blade attached to the plunger.

  As shown in FIG. 9, in the saver saw 200, a reciprocating plate 218 that converts rotational motion into reciprocating motion is attached to a second shaft 209 that is rotationally driven by a drive gear 208 provided on a motor shaft 207 of an electric motor 201. It has been. Plunger 220 with blade 227 attached to the tip is slidably attached inside bearing metal 219 attached to gear cover 206, and is reciprocated by reciprocating plate 218 as second shaft 209 rotates. The reciprocating direction of the plunger 220 and the rotation axis of the second shaft 209 are arranged in parallel. A saver saw 200 having such a configuration is described in, for example, Japanese Patent Application Laid-Open No. 2002-79417.

The operation of the saver saw 200 having the above-described configuration will be described with reference to FIGS. The plunger 220 performs one reciprocation as shown in FIGS. When the plunger 220 is moving in the right direction of the drawing as shown in FIGS. 10 to 12 and when the plunger 220 is moving in the left direction as shown in FIGS. Further, as shown in FIGS. 10, 12, 13, and 15, the forces F1 and F2 are applied, respectively. When the rear end of the plunger 220 is lifted upward by the force of F1, a force F3 that presses the blade 227 against the material to be cut works with a position near the connection position between the plunger 220 and the blade 227 as a fulcrum. This force is used as a force for pressing the blade 227 against the workpiece P in order to cut the workpiece P, so that the cutting can be performed efficiently.
JP 2002-79417 A

  However, when the rear end of the plunger 220 is lowered downward with the position in the vicinity of the connection position between the plunger 220 and the blade 227 as a fulcrum by the force F2, the force F4 moves in a direction in which the blade 227 tends to move away from the workpiece P. Work. When such a force F4 is generated, it is difficult to press the blade 227 firmly against the material P to be cut, and this becomes a factor in reducing cutting performance.

  Then, an object of this invention is to provide the electric tool which improved the cutting performance by reducing the force which acts on the braid | blade in the direction which leaves | separates from a to-be-cut material as much as possible.

  In order to solve the above-described problems, the present invention provides a housing that houses a motor, a drive shaft that is rotatably supported by the housing and that is driven to rotate by the motor, and is supported so as to be reciprocally movable relative to the housing. A reciprocating member; and a drive converting means coupled to the drive shaft and the reciprocating member, and converting a rotational motion of the drive shaft into a reciprocating motion of the reciprocating member, the drive shaft and the reciprocating member Provides a power tool in which a virtual extension line of the axis of the drive shaft and a virtual extension line of the axis of the reciprocating member intersect at a predetermined angle.

  The drive shaft and the reciprocating member are connected to the reciprocating member because the virtual extension line of the axis of the driving shaft and the virtual extension line of the reciprocating member intersect at a predetermined angle. The locus of the portion of the conversion means connected to the reciprocating member when the virtual extension of the axis of the drive shaft and the virtual extension of the axis of the reciprocating member are parallel to each other. It can be changed to a different trajectory. For this reason, during the reciprocating motion, the direction in which the reciprocating motion member is pressed can be changed by the portion of the motion converting means connected to the reciprocating motion member. As a result, for example, when the electric tool is applied to a saver saw or the like, by adjusting the predetermined angle, it is possible to increase the force to press the teeth of the blade of the saver saw against the workpiece, It can cut efficiently.

  Here, the reciprocating member is composed of a plunger that can be fitted with a blade at the distal end, and the motion converting means includes an eccentric shaft through which the drive shaft is inserted, and a base end portion supported by the eccentric shaft. The tip of the reciprocating plate engages with the plunger, and the tip of the reciprocating plate draws a trajectory that forms part of an arc as the reciprocating plate swings. The predetermined angle is such that the tip end virtually bisects the locus when the direction connecting the base end and the tip end of the reciprocating plate is perpendicular to the direction of the axis of the plunger. In this case, it is preferable that the angle value is such that one of the bisected trajectories is three times or more of the other length.

  The reciprocating member comprises a plunger that can be fitted with a blade at the tip, and the motion converting means includes an eccentric shaft through which the drive shaft is inserted, and a reciprocating plate whose base end is supported by the eccentric shaft and is swung by the eccentric shaft. Since the tip of the reciprocating plate is engaged with the plunger, the power tool can be configured as a saver saw.

  Further, the predetermined angle is obtained when the tip virtually bisects the locus when the direction connecting the base end and the tip of the reciprocating plate is perpendicular to the direction of the axis of the plunger. Since the angle of one of the halved trajectories is more than three times the length of the other, the section where the pressing force is applied to the material to be cut on the blade of the saver saw blade It is possible to make it 3 times or more of the section where the force for separating the teeth from the material to be cut is acting, and it is possible to efficiently cut with a saver saw.

  Also, the direction from the axial center position of the plunger to the axial center position of the drive shaft is the downward direction, the direction from the tip of the reciprocating plate to the tip of the plunger is the forward direction, and the teeth of the blade are It is preferable that one of the trajectories is positioned in front of the other.

  The direction from the axial center position of the plunger to the axial center position of the drive shaft is the downward direction, the direction from the tip of the reciprocating plate to the tip of the plunger is the forward direction, and the blade teeth are attached facing downward. Since one of the trajectories is located in front of the other, cutting can be performed efficiently when the blade teeth are directed downward.

  The other length of the locus is preferably substantially zero. Since the other length of the trajectory is substantially zero, when the blade is moving in the direction opposite to the front direction, that is, in the rear direction, generation of force acting in the direction in which the blade is separated from the workpiece is generated. Can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the electric tool which reduced the force which works to the direction which leaves | separates from a to-be-cut material to a blade as much as possible, and improved cutting performance can be provided.

  A saver saw as an electric tool according to an embodiment of the present invention will be described with reference to FIGS. The saver saw 100 mainly includes a motor unit, a speed reduction unit, a plunger rotation-reciprocation conversion unit, a plunger holding mechanism unit, a blade holding unit, and a main body front holding unit. In the following, for convenience of explanation, the direction from the distal end portion of the plunger 20 described later to the spherical portion 18b as the distal end portion of the reciprocating plate 18 described later, that is, the right direction in FIG. The direction toward the tip of the plunger 20, that is, the left direction in FIG. 1, is the front direction, and the direction from the axial center position of the drive rotation shaft 9A described later to the axial center position of the plunger 20 described later, that is, the upward direction in FIG. Is the upward direction, and the direction from the axial center position of the plunger 20 toward the axial center position of the drive rotating shaft 9A, that is, the downward direction in FIG.

  (Motor part) The motor part has the electric motor 1 as FIG. 1 shows, and the electric motor 1 is incorporated in the motor housing 2 made of resin. The motor shaft 7 of the electric motor 1 extends to a speed reduction unit described later. A handle 3 is connected to the rear of the motor housing 2. The handle 3 has a built-in switch 4 for controlling power supply to the electric motor 1.

  (Deceleration part) The reduction part is arranged in front of the motor housing 2. A power transmission means described below is built in, and an aluminum inner cover 5 and a gear cover 6 connected to the front of the motor housing 2 are provided. A drive gear 8 is fixed to the tip of the motor shaft 7 so as to be rotatable together with the motor shaft 7. A second shaft 9 extending in parallel with the motor shaft 7 is provided in the speed reduction portion, and a driven gear 10 is coaxially attached to the second shaft 9 so as to be integrally rotatable with the second shaft 9. The electric motor 1 rotationally drives the second shaft 9 by the pair of reduction gears (the drive gear 8 and the driven gear 10). The motor housing 2, the inner cover 5, and the gear cover 6 constitute the housing of the present invention.

  As shown in FIG. 1, the second shaft 9 has an inclined shaft described later provided with an inclined surface having a predetermined angle with respect to the axis of the driven gear 10 so that the plunger 20 described later can be reciprocated. 9a is provided. As shown in FIG. 1, the second shaft 9 has a drive rotation shaft 9 </ b> A and a spacer 9 </ b> B provided so as to be integrally rotatable. The longitudinal direction of the drive rotary shaft 9A is oriented parallel to the motor shaft 7, and as shown in FIG. 3, a virtual extension line of the axis of the plunger 20 described later and the axis of the drive rotary shaft 9A. And the virtual extension line form a positional relationship that intersects at a predetermined angle β. In FIG. 3, since the intersecting intersection is in the right direction outside the figure, it does not appear in FIG. At one end of the drive rotary shaft 9A, a bearing supported portion 9c that is rotatably supported by the inner cover 5 via a bearing 9G is provided on the drive rotary shaft 9A so as to be rotatable integrally with the drive rotary shaft 9A.

  The spacer 9B is provided in the vicinity of the other end of the drive rotary shaft 9A, and the thickness of the spacer 9B in the axial direction of the drive rotary shaft 9A is a predetermined value that can avoid contact between the driven gear 10 and the eccentric shaft 9a. It has become. A driven gear 10 is provided closer to the other end of the drive rotary shaft 9A than the spacer 9B so as to be able to rotate integrally with the drive rotary shaft 9A. The other end 9E closer to the other end than the driven gear 10 is rotatably supported by the inner cover 5 via a bearing 9F as shown in FIG. The second shaft 9 corresponds to a drive shaft.

  (Plunger holding mechanism) A bearing metal 19 is fixed to the front inside of the gear cover 6, and a plunger 20 is attached so as to reciprocate through the bearing metal 19. As shown in FIG. 2, a roller shaft 21 penetrating the plunger 20 is rotatably attached to the plunger 20, and the roller shaft 21 is provided so as to reciprocate integrally with the plunger 20. Further, a total of two rollers 23 are attached to each end of the roller shaft 21 so as to be rotatable. Inside the gear cover 6, raceway surfaces 6 a and 6 b having two surface widths slightly larger than the outer diameter of the roller 23 are provided, and rotation of the plunger 20 in the circumferential direction is performed via the roller shaft 21 and the roller 23. It is suppressed by the two raceway surfaces 6a and 6b to prevent the blade 27 described later from falling. The plunger 20 corresponds to a reciprocating member.

  (Blade holding part) The blade holder part 24 in front of the plunger 20 can be attached to and detached from the blade 27 having teeth 27A capable of cutting the material P (FIG. 3 and the like) by a lever operation (not shown) that can be rotated. It is configured. The blade 27 can be mounted with the teeth 27A of the blade 27 facing upward, and the blade 27 can be mounted with the teeth 27A of the blade 27 facing downward. Has been. Moreover, the structure which fixes the braid | blade 27 with a volt | bolt is also employable.

  (Main body front holding portion) A front cover 26 made of an insulating heat insulating elastic member having a large coefficient of friction is provided outside a part of the inner cover 5, the gear cover 6 and the motor housing 2. A base 25 that stabilizes the saver saw body against the material to be cut P during the cutting operation is fixed to the tip of the gear cover 6.

  (Plunger rotation-reciprocation conversion portion) As shown in FIG. 1, the second shaft 9 is provided with the above-described eccentric shaft 9a so as to surround the periphery thereof. A through hole is formed in the eccentric shaft 9a, and the second shaft 9 is inserted through the through hole. The eccentric shaft 9a has an inclined shaft portion surface 9H that is an inclined surface, and the eccentric shaft 9a has a reciprocating plate 18 having a swing shaft portion 18a via two bearings 17 in contact with the inclined shaft portion surface 9H. The base end of is attached. An angle α (FIG. 3) formed by the inclined shaft portion surface 9H and the axis of the drive rotation shaft 9A is equal to the predetermined angle β described above. A spherical portion 18b is provided at the tip of the swing shaft portion 18a. The spherical portion 18b passes through the plunger 20 and engages with the inside of the hole portion 20a so as to be able to roll with a slight gap. The eccentric shaft 9a and the reciprocating plate 18 are configured to transmit the rotational movement of the second shaft 9 to the plunger 20. Convert to reciprocating motion. The eccentric shaft 9a and the reciprocating plate 18 correspond to motion conversion means.

  The reciprocating plate 18 is swung by the eccentric shaft 9a as the drive rotating shaft 9A rotates. The swinging is performed at a crossing point A between the direction of connecting the spherical portion 18b, which is the tip of the reciprocating plate 18, and the portion of the reciprocating plate 18 supported by the bearing 17 that forms the base, and the drive rotating shaft 9A. It is performed in the front-rear direction as the axis of movement. Accordingly, the spherical portion 18b draws a trajectory that forms a part of an arc around the axis of oscillation as the reciprocating plate 18 swings. More specifically, the position shown in FIG. 3 is the foremost end position of the spherical portion 18b and the position shown in FIG. 5 is the rearmost end position of the spherical portion 18b. Draw a trajectory like drawing an arc.

  As shown in FIG. 5, the predetermined angle β described above has a positional relationship in which the direction connecting the base end portion of the reciprocating plate 18 and the spherical portion 18b as the tip end portion and the direction of the axis of the plunger 20 are perpendicular to each other. Sometimes, when the spherical portion 18b virtually bisects the trajectory, an angle value is taken such that one of the bisected trajectories is at least three times as long as the other. In the present embodiment, since the vertical positional relationship is at the rearmost position shown in FIG. 5, when it is considered that the trajectory is divided into two, one length of the trajectory is equal to the entire trajectory. The other length is zero. For this reason, one length of the bisected trajectory is infinitely larger than the other length. At this time, the one length is located on the front side of the other length.

  Therefore, the spherical portion 18b does not retract backward from the state of FIG. 5, and the rear end of the plunger 20 is prevented from being pushed downward obliquely downward in FIG. be able to. As a result, it is possible to prevent the force F4 as shown in FIG. 15 from acting on the blade 27 described later in a direction in which the force F4 tends to be separated from the material to be cut P. Can be cut.

  (Explanation of cutting operation by reciprocating motion) When the blade 27 of the saver saw is cutting the workpiece P and is in the state shown in FIG. 3, the spherical portion 18b of the reciprocating plate 18 is positioned at the foremost end. is doing. From this position, as shown in FIGS. 3 to 5, the reciprocating plate 18 is swung with the intersection point A as a swinging axis, and the spherical portion 18b moves while drawing a locus in a substantially upper right direction in FIG. Go. Then, as shown in FIG. 5, when the positional relationship in which the direction connecting the base end portion of the reciprocating plate 18 and the spherical portion 18 b is perpendicular to the direction of the axis of the plunger 20, The spherical portion 18b is located at the end.

  While the swinging shown in FIGS. 3 to 5 is performed, the spherical portion 18b moves in a substantially upper right direction in the drawing as described above, so that the plunger as shown in FIGS. A force F1 acts on the rear end of the blade 20 in the same direction, and a force F3 acts on the blade 27 with a position near the connection position between the plunger 20 and the blade 27 as a fulcrum. F3 acts as a force for pressing the blade 27 against the workpiece P. In addition, since the blade 27 at this time is moving from the front direction to the rear direction, this movement is the direction in which the workpiece P is cut by the teeth 27A, and the force of F3 acts on the blade 27. Thus, the workpiece P can be efficiently cut.

  Thereafter, the reciprocating plate 18 is turned in the swinging direction from the state shown in FIG. 5, and starts swinging in the left direction of the drawing as shown in FIG. From this position, as shown in FIGS. 6 to 8, the reciprocating plate 18 is oscillated around the intersection A as the axis of oscillation, and the spherical portion 18b draws a locus in the substantially lower left direction of FIG. Move. When the state shown in FIG. 8 is reached, the spherical portion 18b is in the foremost end position, the swing direction of the reciprocating plate 18 is folded back, and the swing shown in FIGS. 3 to 5 is performed again.

  Since the blade 27 is moving from the rear direction to the front direction while the swinging shown in FIGS. 6 to 8 is being performed, the material P to be cut is not much during this movement due to the direction of the teeth 27A. Not cut off. At this time, as described above, since the spherical portion 18b moves in a substantially lower left direction in the figure, as shown in FIGS. 7 and 8, a force F2 acts on the rear end of the plunger 20 in the same direction, A force F4 acts on the blade 27 with a position in the vicinity of the connection position between the plunger 20 and the blade 27 as a fulcrum. F4 is a force acting in a direction away from the material to be cut P, but the material to be cut P is not cut much while the swinging shown in FIGS. 6 to 8 is performed as described above. Even if the force of F4 is applied, it hardly affects the cutting of the material P to be cut.

  As shown in FIG. 5, the predetermined angle β (FIG. 3) is a position where the direction connecting the base end portion of the reciprocating plate 18 and the spherical portion 18 b as the tip end portion is perpendicular to the axial center direction of the plunger 20. When the spherical portion 18b virtually bisects the locus of the spherical portion 18b at the time of the relationship, the angle value is such that one length of the bisected locus is an infinite multiple of the other length. Therefore, when the blade 27 is moving in the rearward direction, a force F3 for pressing the blade 27 against the workpiece P can always be applied to the blade 27. It is possible to prevent the force from always acting on the blade 27. For this reason, the to-be-cut material P can be cut | disconnected efficiently at the time of the movement to the back of the blade 27 which mainly cuts the to-be-cut material P. As shown in FIG.

  The power tool of 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. For example, in the present embodiment, the predetermined angle β (FIG. 3) is such that the direction connecting the base end portion of the reciprocating plate 18 and the spherical portion 18b as the tip portion and the axial center of the plunger 20 as shown in FIG. When the spherical portion 18b virtually bisects the trajectory of the spherical portion 18b, the length of one of the bisecting trajectories is an infinite multiple of the other length. However, the present invention is not limited to this value. For example, even if the value is three times, the section in which the force F3 is applied while the blade 27 moves from the front end to the rear end is set to be three times the section in which the force F4 is applied. Therefore, the force F3 can be sufficiently applied to the blade 27, and the workpiece P can be cut efficiently. Thus, it is preferable that it is 3 times or more.

  Further, as shown in FIGS. 1 to 8, in the case of the configuration in which the direction of the teeth 27A of the blade 27 is upward, it is one of the trajectories of the bisected spherical portion 18b and is located in the rearward direction. It is desirable that the length be longer than the length of the other part of the locus of the bisected spherical portion 18b and located in the forward direction.

  In the present embodiment, the blade 27 is configured to reciprocate linearly when reciprocating. However, as disclosed in Japanese Patent Application Laid-Open No. 2002-79417, the blade 27 is slightly not linear. An orbital cutting operation may be performed by reciprocating in an arc.

  Further, even if the plunger 20 moves slightly in the direction crossing the reciprocating direction due to rattling or the like or the orbital cutting operation as described above, the axis of the plunger 20 and the axis of the second shaft 9 are not aligned. It is desirable that the axis of the second shaft 9 is inclined with respect to the axis of the plunger 20 to such an extent that it does not become parallel.

  Further, in order to cancel the vibration generated by the reciprocating motion of the plunger 20, a balance weight that performs a reversal motion with respect to the plunger 20 in the axial direction of the plunger 20, that is, a motion that is 180 degrees out of phase may be provided. Moreover, although this Embodiment demonstrated the saver saw as an electric tool, this invention is applicable also to electric tools other than a saver saw.

The partial cross section side view which shows the saver saw which is an electric tool by embodiment of this invention. Sectional drawing along the II-II line of FIG. The conceptual diagram which shows the cutting | disconnection locus | trajectory in the saver saw which is an electric tool by embodiment of this invention, and shows the state in which the braid | blade is located most forward. The conceptual diagram which shows the cutting locus in the saver saw which is an electric tool by embodiment of this invention, and shows the state which has a braid | blade in the approximate center position of reciprocation. The conceptual diagram which shows the cutting locus in the saver saw which is an electric tool by embodiment of this invention, and shows the state in which the braid | blade is located in the backmost part. The conceptual diagram which shows the cutting locus in the saver saw which is an electric tool by embodiment of this invention, and shows the state in which the braid | blade is located in the backmost part. The conceptual diagram which shows the cutting locus in the saver saw which is an electric tool by embodiment of this invention, and shows the state which has a braid | blade in the approximate center position of reciprocation. The conceptual diagram which shows the cutting | disconnection locus | trajectory in the saver saw which is an electric tool by embodiment of this invention, and shows the state in which the braid | blade is located most forward. The partial cross section side view which shows the saver saw which is the conventional electric tool. The conceptual diagram which shows the cutting locus in the saver saw which is the conventional electric tool, and shows the state in which the braid | blade is located in the foremost. The conceptual diagram which shows the cutting locus in the saver saw which is the conventional electric tool, and shows the state which has a braid | blade in the approximate center position of reciprocation. The conceptual diagram which shows the cutting | disconnection locus | trajectory in the saver saw which is the conventional electric tool, and shows the state in which the braid | blade is located in the backmost part. The conceptual diagram which shows the cutting | disconnection locus | trajectory in the saver saw which is the conventional electric tool, and shows the state in which the braid | blade is located in the backmost part. The conceptual diagram which shows the cutting locus in the saver saw which is the conventional electric tool, and shows the state which has a braid | blade in the approximate center position of reciprocation. The conceptual diagram which shows the cutting locus in the saver saw which is the conventional electric tool, and shows the state in which the braid | blade is located in the foremost.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric motor 2 ... Motor housing 5 ... Inner cover 6 ... Gear cover 9 ... Second shaft 9a ... Eccentric shaft 18 ... Reciprocating plate 20 ... Plunger 27 ... Blade 100 ... Saber saw

Claims (4)

A housing for housing the motor;
A drive shaft rotatably supported by the housing and driven to rotate by the motor;
A reciprocating member supported so as to reciprocate with respect to the housing;
A motion conversion means connected to the drive shaft and the reciprocating member, and converting a rotational motion of the drive shaft into a reciprocating motion of the reciprocating member;
The drive shaft and the reciprocating member have a positional relationship in which a virtual extension line of the axis of the drive shaft and a virtual extension line of the axis of the reciprocating member intersect at a predetermined angle. A power tool. The reciprocating member is composed of a plunger that can be fitted with a blade at the tip,
The motion conversion means has an eccentric shaft through which the drive shaft is inserted, and a reciprocating plate whose base end is supported by the eccentric shaft and is swung by the eccentric shaft,
The tip of the reciprocating plate engages with the plunger, and the tip of the reciprocating plate draws a trajectory that forms part of an arc as the reciprocating plate swings,
When the predetermined angle is a positional relationship in which the direction connecting the base end and the tip of the reciprocating plate is perpendicular to the direction of the axis of the plunger, the tip virtually bisects the locus. The power tool according to claim 1, wherein an angle value is set such that one length of the bisected trajectory is three times or more of the other length. The direction from the axial position of the plunger toward the axial position of the drive shaft is the downward direction, the direction from the tip of the reciprocating plate to the tip of the plunger is the forward direction,
3. The electric tool according to claim 2, wherein the teeth of the blade are attached facing downward, and one of the trajectories is located in front of the other.   4. The electric tool according to claim 3, wherein the other length of the locus is substantially zero.

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