JP2011020205A - Portable cutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a protective cover from moving in an unintended direction of a worker in a portable cutter having a movable protective cover. <P>SOLUTION: The portable cutter (1) has a motor, a cutting means (5) driven by the motor, a housing (7) for storing the motor, and the movable protective cover (11) mounted on the housing and covering the exposed part of the cutting means during non-cutting work. The portable cutter further has an acceleration sensor (31) for detecting the attitude change of the portable cutter and a lock mechanism 16 for restricting the movement of the protective cover (11) when the abrupt attitude change of the portable cutter is detected by the acceleration sensor (31) during cutting work. After the abrupt attitude change of the portable cutter (1) is detected by the acceleration sensor 31, secondary movement of the protective cover (11) automatically restored to a normal state (closed state) is restricted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a portable cutting machine, and more particularly to a lock mechanism for a protective cover of a portable cutting machine having a movable protective cover that covers an exposed portion of a cutting means.

  For example, Patent Document 1 discloses a portable cutting machine having a movable protective cover that covers an exposed portion of the cutting means. The configuration of this conventional portable cutting machine will be described with reference to FIGS. 17 and 18, a circular saw device 201 is used as an example of a portable cutting machine. The circular saw device 201 uses a motor 202 as a drive source, and cuts a material to be cut by rotating a saw blade 205 (FIG. 18) that is rotationally driven by a motor 202 via a speed reduction unit (not shown). is there. The housing of the circular saw device 201 includes a motor housing 204 for housing the motor 202 and an upper cover (fixed) that substantially covers the upper half of the saw blade 205 and the upper side of the blade edge portion 206 of the saw blade 205. The cover 207 is mainly composed of two members. The motor housing 204 is formed with a handle portion 204A that extends in a direction perpendicular to the rotation axis of the motor 202 and is gripped by an operator. The handle portion 204A includes a trigger switch (for controlling driving of the motor 202). (Not shown) is provided.

  A base 210 having an opening 210B for projecting the saw blade 205 downward from the bottom surface 210A is provided at the lower portion of the upper cover 207. As shown in FIG. 18, the base 210 has a flat bottom surface 210A so that the circular saw device 201 can slide on the workpiece during a cutting operation. Further, a lower cover (movable cover, protective cover) 211 is attached to the housing. The lower cover 211 is configured to substantially cover the side of the lower half of the saw blade 205 that protrudes from the bottom surface 210A when the cutting operation is not performed, and the outer edge side of the blade edge portion 206. When the cover 211 comes into contact with the workpiece, the cover 211 is accommodated in the upper cover 207, and a part of the blade edge portion 206 is exposed to a certain amount below the base 210. The lower cover 211 is rotatably supported in the upper cover 207 and is biased by a spring 212 when the cutting operation is not performed, and the lower cover 211 rotates in a direction to cover the blade edge portion 206. The upper cover 207 is provided with a stopper 214 formed of a cushioning material fixed by a screw 213, and the biased lower cover 211 is limited in contact with the stopper 214 to limit the movement range thereof.

JP 08-14001 A

  The portable cutting machine as described above is configured such that the lower cover 211 substantially covers the exposed portion of the saw blade 205 when the cutting operation is not performed. During the cutting operation, if the so-called kickback in which the portable cutting machine itself bounces back from the workpiece due to the reaction of the cutting edge portion 206 biting into the workpiece, the lower cover 211 immediately moves and the workpiece is processed. It returns to a position (protection position (closed state): position of the lower cover 211 shown in FIG. 18) that substantially covers the exposed portion of the saw blade 205 away from the material. However, when the portable cutting machine itself moves away from the workpiece, if the lower cover 211 rotates for some reason in contact with surrounding structures or materials, the blade edge 206 is exposed. It may damage the crops and materials.

  The present invention has been made in view of the above background, and an object thereof is a portable cutting machine having a movable protective cover, in which the protective cover can be prevented from moving in a direction unintended by the operator. To provide a cutting machine.

  Another object of the present invention is to provide a portable cutting machine that realizes a lock mechanism that detects an abnormal movement of the portable cutting machine and fixes a protective cover in a protected position.

  Still another object of the present invention is to provide a portable cutting machine that realizes a movable protective cover locking mechanism with a simple structure.

  Of the inventions disclosed in the present application, typical features will be described as follows.

  According to one aspect of the present invention, a motor, a cutting means driven by the motor, a housing that houses the motor, and a base that is attached to the housing and that slides on a workpiece that is cut by the cutting means, A portable cutting machine having a closed cover that covers the outer periphery of the cutting means that is attached to the housing and protrudes from the base, and a protective cover that is rotatable in an open state that exposes the outer periphery. The detection means for detecting the posture change and the protective cover is controlled to be closed when the protective cover is changed from the open state to the closed state after detecting a sudden posture change of the portable cutting machine during the cutting operation. A locking mechanism is provided. After detecting a sudden posture change of the portable cutting machine by the detecting means, it is configured to restrict the re-movement of the protective cover that has automatically returned to the initial state (closed state).

  According to another aspect of the present invention, the protective cover is an automatic return type that automatically returns to the steady position and covers the exposed portion of the cutting means when the portable cutting machine leaves the workpiece. After detecting the sudden posture change of the cutting machine, the lock mechanism limits the movement of the protective cover after the protective cover returns to the steady position (closed state). The motor used in the portable cutting machine is a brushless DC motor, and is provided with a control means for controlling the rotation of the brushless DC motor, and the control means is configured to control the operation of the lock mechanism using the output of the detection means. It is preferable. The detection means is an acceleration sensor provided in the housing, and detects the magnitude of acceleration applied to the portable cutting machine.

  According to still another aspect of the present invention, the portable cutting machine is a portable circular saw device, and the protective cover is a cover that moves circumferentially along the outer periphery of the circular saw blade, The mechanism is provided on the outer peripheral side of the movement range of the protective cover. The lock mechanism has a solenoid and a solenoid pin moved by the solenoid, and restricts the movement of the protective cover by contacting the protective cover when the solenoid pin moves. Further, it is preferable to provide a stepped portion on the outer edge of the protective cover that allows the protective cover to move only in one direction when the lock mechanism is operated.

  According to still another aspect of the present invention, the control unit includes a control unit that controls the operation of the lock mechanism, and a protrusion amount changing unit that changes a protruding amount of the cutting unit from the bottom surface of the base. The lock mechanism is controlled in accordance with the protrusion amount set by. The detection means detects the current flowing through the motor or the rotation speed of the motor, and the control means controls the lock mechanism in accordance with a signal from the detection means.

  According to the first aspect of the present invention, since the lock mechanism for restricting the movement of the protective cover is provided after detecting a sudden posture change of the portable cutting machine by the detecting means during the cutting operation, the blade edge portion is exposed. It is possible to realize a portable cutting machine that can suppress the damage to the crops and materials.

  According to the second aspect of the present invention, since the movement of the protective cover is restricted and the motor is stopped after the sudden change in the posture of the portable cutting machine is detected by the detecting means, the cutting edge portion is exposed and the structure is made. A portable cutting machine that can suppress damage to crops and materials can be realized.

  According to the invention of claim 3, the protective cover is an automatic return type, and after detecting a sudden change in posture of the portable cutting machine, the lock mechanism protects after the protective cover returns to the steady position (closed state). Since the movement of the cover is limited, the movement of the protective cover can be locked in a state where the cover is reliably returned to the protected position.

  According to the invention of claim 4, since the control means for controlling the rotation of the brushless DC motor is provided, and the control means controls the operation of the lock mechanism using the output of the detection means, a dedicated microcomputer for the lock mechanism is provided. Since there is no need to prepare a control device, the manufacturing cost can be minimized.

  According to the invention of claim 5, since the detecting means is an acceleration sensor and detects the magnitude of acceleration applied to the portable cutting machine, the lock mechanism of the present invention can be realized using an inexpensive sensor. .

  According to the invention of claim 6, the portable cutting machine is a portable circular saw device, and locks the cover that moves in the circumferential direction along the outer periphery of the circular saw blade, so that the protective cover can be securely attached. A circular saw device that can be locked can be realized.

  According to the invention of claim 7, the lock mechanism has a solenoid and a solenoid pin moved by the solenoid, and restricts the movement of the protective cover by contacting the protective cover when the solenoid pin moves. A lock mechanism can be realized with a simple structure.

  According to the eighth aspect of the present invention, the outer edge of the protective cover is provided with a step portion that allows movement in only one direction when the lock mechanism is operated. Even if the return of the lock is delayed, the lock mechanism does not hinder the return.

  According to the ninth and tenth aspects of the present invention, since the lock mechanism is controlled according to the protruding amount of the cutting means from the base bottom surface, various protruding amounts (cut depths) can be dealt with.

  According to the eleventh aspect of the invention, since a sudden change in posture of the portable cutting machine is detected based on the motor current or the motor speed, there is no need to provide a separate detection means, and the structure or material is damaged by an inexpensive configuration. Therefore, it is possible to realize a portable cutting machine that can suppress the occurrence.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

It is a top view of the circular saw apparatus which concerns on the Example of this invention, and shows one part in the cross section. It is a side view of the circular saw apparatus which concerns on the Example of this invention, and shows a part in the cross section. It is an expanded sectional view of the lock mechanism part 16 of FIG. It is a figure which shows the state by which the electronic element was mounted in the board | substrate 18, (1) is the side view seen from the side of the board | substrate 18, (2) is the rear view seen from back. It is a figure which shows the shape of the upper case 22, (1) is a rear view seen from back, (2) is sectional drawing of the AA part of (1). It is a figure which shows the shape of the lower case 23, (1) is a rear view seen from back, (2) is sectional drawing of the BB part of (1). It is a block diagram which shows the circuit structure of the locking mechanism part 16 which concerns on the Example of this invention. 6 is a flowchart for explaining the operation of the lock mechanism section 16; It is an expanded sectional view of the lock mechanism part 56 which concerns on the 2nd Example of this invention. It is a figure which shows the assembly structure of the locking member 70 of FIG. 9, (1) is the figure seen from the side surface, (2) is the top view seen from the top. It is an expanded sectional view of the lock mechanism part 56 which concerns on 2nd Example of this invention, and the condition which the lock mechanism part 56 act | operated is shown. It is an expanded sectional view of the lock mechanism part 56 concerning the 2nd example of the present invention, and is another figure showing the situation where lock mechanism part 56 operated. It is a figure which shows the partial shape of the protective cover 61 of FIG. 9, (1) is a rear view, (2) is a side view. It is a top view of the circular saw apparatus concerning the 3rd Example of this invention, and shows a part in the cross section. It is a block diagram which shows the structure of the drive control system of the brushless DC motor 102 of FIG. It is a time chart which shows the motor current and motor rotation speed at the time of the attitude | position change of the circular saw apparatus based on the Example of this invention having arisen. It is a top view of the conventional circular saw apparatus, A part is shown in the cross section. It is a side view of the conventional circular saw apparatus, and shows a part in the cross section.

  Hereinafter, a portable cutting machine according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an electric circular saw device 1 will be described as an example of a portable cutting machine. In the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. Further, in this specification, the description will be made assuming that the direction in which the circular saw device 1 is moved during cutting is the front direction, and that the front, rear, left, right, and up and down directions are the directions shown in FIGS.

  FIG. 1 is a top view of a circular saw device 1 according to an embodiment of the present invention, and a part thereof is shown in a sectional view. The circular saw device 1 uses an electric motor 2 as a drive unit. A housing that shapes the outer shape of the circular saw device 1 includes a motor housing 4 that houses the motor 2, and a right side of the motor housing 4, and an upper cover 7 that is provided in a direction orthogonal to the rotation axis of the motor 2. Mainly composed. The motor housing 4 is integrally formed with a handle portion 4A for an operator to hold, and the handle portion 4A is provided with a trigger switch (not shown) for controlling the driving of the motor 2. The handle portion 4A is further provided with an on-lock switch 3 for keeping the trigger switch on. The upper cover 7 has a base 10 that has a bottom surface that is slidable on the workpiece and that defines a reference position for the cutting operation. In order to adjust the exposure amount of the base 10 so that a part of the saw blade 5 is exposed on the lower side of the base by engaging the upper cover 7 with the locking portion 8 provided on the base 10. Used for. A part of the base 10 is formed with an opening 10 </ b> B for allowing the saw blade 5 to penetrate downward from the bottom surface to be protruded.

  FIG. 2 is a right side view of the circular saw device 1 according to the embodiment of the present invention, and a part thereof is shown in a sectional view. The saw blade 5 is rotationally driven by the motor 2 via a speed reduction portion (not shown). The rotation direction of the saw blade 5 is counterclockwise when viewed in FIG. 2, and a plurality of blade tip portions 6 are formed on the outer peripheral portion of the saw blade 5. The upper cover 7 is attached to the motor housing 4 (see FIG. 1), covers substantially the entire motor 2 side of the upper half of the saw blade 5, and covers the vicinity of the upper outer periphery of the cutting edge portion 6 of the saw blade 5. The base 10 is pivotally supported by the upper cover 7 so that the rear side can be rotated, and the front side is attached to the upper cover 7 via a locking portion 8 that is fixed by changing the relative positions of the upper cover 7 and the base 10. Fixed. The base 10 has a bottom surface 10A that can slide on the workpiece, and is provided at a position where the saw blade 5 can protrude downward from the bottom surface 10A. The amount of the saw blade 5 projecting downward from the bottom surface 10A is desired by using the locking portion 8 as a fulcrum by a notch depth adjusting mechanism (not shown) provided in the upper cover 7 on the rear side of the base 10. It can be adjusted by tightening the cut adjustment lever 8A (see FIG. 1) after adjusting the cut amount.

  The housing is provided with a lower cover 11 that covers the saw blade 5 when a cutting operation is not performed. The lower cover 11 is configured to substantially cover the side surface on the motor 2 side of the saw blade 5 protruding from the bottom surface 10 </ b> A and to cover the periphery on the outer peripheral side of the exposed blade edge portion 6. At the time of the cutting operation, the front end portion 11A of the lower cover 11 abuts on the workpiece, so that the lower cover 11 moves clockwise along the outer edge of the saw blade 5 in FIG. The upper cover 7 is accommodated by moving to a position having the same height as the bottom surface 10A. In order to enable the lower cover 11 to rotate in the upper cover 7 in this way, the lower cover 11 is attached counterclockwise by the spring 12 so as to rotate in a direction to cover the blade edge portion 6 when the cutting operation is not performed. The upper portion of the tip portion 11A comes into contact with the cushioning material 14 fixed to the upper cover 7 with the screw 13, and only a part of the blade edge portion 6 is exposed on the lower side of the base 10 as shown in FIG. It becomes a state. In this specification, the position of the lower cover 11 in this state is referred to as “steady position”, “protection position”, or “closed state”.

  A lock mechanism 16 is fixed to the inner wall 7 </ b> A on the rear end side of the upper cover 7 with a screw 17. The lock mechanism 16 includes a sensor that detects a change in the posture of the circular saw device 1, and for some reason, the circular saw device is rebounded from the workpiece by the reaction of the blade edge portion 6 biting into the workpiece. When a sudden posture change occurs in the circular saw device, the lower cover 11 that has returned to the steady position is locked so as not to rotate. The lock mechanism portion 16 includes a solenoid pin 21 that moves in the radial direction of the saw blade by the solenoid 20, and the solenoid pin 21 moves forward, so that the lock mechanism portion 16 is located inside the region outside the region in which the lower cover 11 moves. It protrudes to the circumferential side and restricts the movement of the rear end portion 11B of the lower cover 11. As a result, even if the lower cover 11 tries to rotate clockwise by some external force from the position of the lower cover 11 shown in FIG. 2, the lower end 11 can move because the rear end portion 11B contacts the solenoid pin 21. Can not.

  FIG. 3 details this state. FIG. 2 is an enlarged cross-sectional view of the lock mechanism portion 16. In FIG. 2, the solenoid pin 21 is in an unlocked state, that is, a state that is located on the rear side, whereas in the enlarged sectional view of FIG. 3, the solenoid pin 21 is in a locked state, that is, in a state that is located on the front side. Indicates that there is. The solenoid pin 21 is a movable iron core of the solenoid 20, converts electric energy supplied by the solenoid 20 into linear motion of the solenoid pin 21, and drives a mechanism (mechanical load) coupled to the movable iron core of the solenoid 20. To do. The solenoid 20 includes a fixed iron core (not shown) that is disposed with a certain gap from the solenoid pin 21 and is wound with a coil. The magnetic force acting between the movable iron core and the mechanical force is given to the solenoid pin 21 in the axial direction. If energization of the coil is continued, the movable iron core is kept attracted to the fixed iron core, but if the current is cut off, it is pulled back to the original position by the force of the recovery spring coupled to the movable iron core.

  The solenoid 20 is mounted on the substrate 18 and is housed in a protective case 19. Solenoid pins 21 of the solenoid 20 disposed on the substrate 18 are formed in holes 23A (see FIG. 6) drilled in the lower case 23 in the upper case 22 and the lower case 23 constituting the protective case 19, and in the inner wall 7A. It passes through the drilled hole 7B and is movable to the internal space of the upper cover 7. When the solenoid pin 21 protrudes in the steady position (closed state) so as to substantially cover the cutting edge 6 from which the lower cover 11 protrudes from the upper cover 7 by the action of the spring 12, if the solenoid pin 21 protrudes, as shown in FIG. The solenoid pin 21 is positioned above the rear end portion 11B, so that the lower cover 11 can be prevented from being stored in the upper cover 7. With this configuration, when the lower cover 11 is moved to a steady position (closed state) for some reason during cutting work, the lower cover 11 is moved to the open state so that the blade edge portion 6 is not opened again. Can be locked. Therefore, even if the circular saw device 1 unexpectedly hits a portion other than the cut portion of the workpiece, it is possible to suppress the workpiece from being damaged by the saw blade 5 without opening the lower cover 11.

  The protective case 19 is composed of two members, a lower case 23 and an upper case 22. A plurality of electronic elements and / or mechanical elements are mounted on the substrate 18 in the protective case 19. 4A and 4B are views showing a state in which the electronic element is mounted on the substrate 18, in which FIG. 4A is a rear view seen from the rear side, and FIG. 4B is a side view seen from the side of the substrate 18. On the substrate 18, a solenoid 20, an acceleration sensor 31, a microcomputer 32, and other electronic elements such as a resistor and a capacitor are mounted. The board 18 is also provided with a power line 27 for obtaining an appropriately transformed power from the board 18 in the motor housing 4 and a signal line 28 for detecting the ON / OFF state of the trigger switch 3. These are respectively pulled out from cutout holes 23C (described later) provided in the lower case 23, and drawn into the motor housing 4 to be connected to predetermined positions.

  5A and 5B are views showing the shape of the upper case 22, wherein FIG. 5A is a rear view seen from the rear side, and FIG. 5B is a cross-sectional view taken along the line AA in FIG. The upper case 22 has a flat basic shape, but a protruding portion 22A protruding in a cylindrical shape is formed in a part thereof. The protruding portion 22A is formed to secure a moving space for the solenoid pin 21 of the solenoid 20 accommodated in the protective case 19, and as shown in FIG. 2, the solenoid pin 21 is in an unlocked state. The rear end portion of the solenoid pin 21 is positioned in the space in the protruding portion 22A.

  FIG. 6 is a view showing the shape of the lower case 23, (1) is a rear view seen from the rear, and (2) is a cross-sectional view of the BB portion of (1). The lower case 23 is combined with the upper case 22 to form a box-shaped protective case 19, and the basic shape of the lower case 23 is a box-like shape with one side open. A hole 23A for penetrating the solenoid pin 21 and a hole 23B for penetrating the screw 17 are formed on the front wall of the lower case 23, and the power line 27 and the signal are formed on the front wall of the lower case 23. A substantially rectangular cut-out hole 23C for drawing out the line 28 is formed. The upper case 22 and the lower case 23 can be made of a synthetic resin such as plastic, for example, and the upper case 22 and the lower case 23 are bonded or bonded by a known bonding means.

  Next, the circuit configuration of the lock mechanism unit 16 according to the embodiment of the present invention will be described with reference to FIG. In the present embodiment, a control unit such as a microcomputer 32, an acceleration sensor 31, and a solenoid 20 are mounted on the substrate 18. The microcomputer 32 includes a storage means 32A and a timer 32B, and an ON / OFF signal of a trigger switch is input. Further, the microcomputer 32 receives an output from the acceleration sensor 31. The output of the acceleration sensor 31 is input to the posture change detection circuit 33, and the signal detected by the posture change detection circuit 33 is output to the microcomputer 32. The microcomputer 32 analyzes the output signal to determine whether the output signal exceeds a threshold value. When the microcomputer 32 detects predetermined acceleration and vibration when the trigger switch 3 is ON, the microcomputer 32 drives the solenoid 20 and moves the solenoid pin 21 to limit the movement of the lower cover 11.

  Next, operation | movement of the locking mechanism part 16 is demonstrated using FIG. First, when the trigger switch of the circular saw device is turned on, the microcomputer 32 determines whether or not there is an output from the acceleration sensor 31 (step 81). Next, the microcomputer 32 waits for a predetermined time by counting the time with the timer 32B (step 82). This is because if the solenoid 20 is immediately driven by the output from the acceleration sensor 31, the solenoid pin 21 protrudes before the lower cover 11 returns to the steady position (closed state) and collides with the outer peripheral portion of the lower cover 11. Because it ends up. The waiting time may be set in consideration of the strength of the spring 12, the moving distance of the lower cover 11, and the like. Next, when a predetermined time elapses, the microcomputer 32 issues a signal for driving the solenoid 21 to move the solenoid pin 21 from one end side (rear side) to the other end side (front side) of the solenoid 20 ( Step 83). At this time, the motor 2 may be controlled to stop.

  Next, the microcomputer 11 detects whether the trigger switch is switched from OFF to ON, and if it is switched, the solenoid 20 is driven, the solenoid pin 21 is returned to the initial position, and the locked state is released, that is, the solenoid 20 is turned off. Reset (steps 84 and 85). When the trigger switch 3 is not switched from OFF to ON, that is, when the solenoid 21 is locked (that is, the trigger switch is ON), the operator keeps holding the trigger switch and opens the trigger switch. If not, or if the operator has released the trigger switch when the solenoid 21 is locked but the trigger switch 3 is not turned on again, the system waits (step 84).

  As described above, in the present embodiment, the circular saw device 1 undergoes a sudden posture change that is not intended by the operator, such as a so-called kickback in which the cutting edge portion 6 is bounced back from the workpiece by the reaction with which the cutting edge 6 is engaged with the workpiece. When this occurs, the acceleration sensor 31 disposed on the substrate 18 detects the change in the behavior, and the microcomputer 32 determines whether or not the change exceeds the threshold value. If the change exceeds the threshold value, the solenoid 20 is operated. . Moreover, since the lower cover 11 is locked after a time required for the lower cover 11 to return to the steady state (closed state), the lower cover 11 is locked in a state in which the lower cover 11 is reliably returned to the steady position (closed state). can do. Therefore, since the re-movement of the lower cover 11 that has returned to the protected state is locked when the posture of the circular saw device 1 is suddenly changed, it is possible to suppress damage to the structure or material by the blade edge portion 6. This device 1 can be realized.

  Next, a lock mechanism 56 according to a second embodiment of the present invention will be described with reference to FIGS. In the figure, the same components as those of the first embodiment described above are denoted by the same reference numerals, and repeated description is omitted. FIG. 9 is an enlarged cross-sectional view of the lock mechanism 56 according to the second embodiment of the present invention. 3 differs from the first embodiment shown in FIG. 3 in the shape of the outer peripheral portion of the lower cover 61 and the structure of the lock member 70.

  FIG. 10 shows an assembly structure of the lock member 70. In FIG. 10, (1) is a view seen from the side, and (2) is a top view seen from above. A spring 73 is placed on a solenoid pin 71 that is a movable iron core of the solenoid 20, and then a lock pin 72 is attached. A through hole 71A penetrating in the vertical direction is formed at the tip of the solenoid pin 71, and a through hole 72C penetrating in the vertical direction is formed in the lock pin 72. As shown in FIG. 10 (2), the through hole 72C has a long hole shape that is flat in the axial direction. When the lock pin 72 is attached to the tip of the solenoid pin 71, the spring 73 is provided on the outer peripheral side of the lock pin 72. The rear side of the spring 73 is in contact with the inner wall 7 </ b> A of the upper cover 7, and the front side is in contact with the rear end surface of the flange portion 72 </ b> A having a partially enlarged diameter of the lock pin 72. By interposing the spring 73 in this way, the lock pin 72 is urged away from the solenoid pin 71 at the normal time. In this state, the fixing pin 74 comes into contact with the inner wall on the rear end side of the through hole 72C. In such a configuration, when an external force that pushes the lock pin 72 backward is applied, the lock pin 72 moves against the repulsive force of the spring 73 until the fixing pin 74 contacts the inner wall on the front end side of the through hole 72C. can do. In addition, the inclined surface 72B formed diagonally is formed in the front end side of the lock pin 72. As shown in FIG. The effect obtained by attaching the movable lock pin 72 to the tip of the solenoid pin 71 in this way will be described with reference to FIGS.

  In FIG. 11, the lower cover 61 moves from the open state where the saw blade 5 is exposed to the protected state (closed state) by the movement of the spring 12, and then the lock member 70 projects forward, The state which protruded above the edge part 61B is shown. In the second embodiment, the positional relationship is such that the vicinity of the tip of the lock pin 72 biased so as to be separated from the solenoid pin 71 protrudes to the moving area of the lower cover 61. A plurality of protrusions (latch portions) 75 are formed on the outer peripheral portion of the lower cover 61. By the way, in step 82 of the flowchart of FIG. 8, the lock member 70 is operated after a predetermined waiting time for locking the lower cover 61. However, when the lower cover 61 comes into contact with the work material or surrounding members and the return to the protected position (closed state) of the lower cover 61 cannot be performed or is delayed for some reason, as shown in FIG. In contact with the outer peripheral surface 61 </ b> C of the lower cover 61. At this time, the lock pin 72 compresses the spring 73 and moves backward toward the solenoid pin 71. Thus, since the lock pin 72 moves relative to the solenoid pin 71, an excessive force is not applied to the solenoid 20, and the durability of the solenoid 20 is improved. On the other hand, since the lock pin 72 is pressed against the lower cover 61 side by using the biasing force of the spring 73, the outer peripheral surface on the lower cover side is not damaged.

  In the second embodiment, when the solenoid 20 is operated and the lock pin 72 is moved forward, the lower cover 61 is not moved in the opening direction (counterclockwise movement, that is, the direction in which the blade edge portion 6 is exposed). It is important to do so. Therefore, the plurality of latch portions 75 are provided on the outer peripheral surface of the lower cover 61 so that the lower cover 61 can rotate only in one direction (clockwise) when the lock pin 72 moves forward. The latch portion 75 includes a flat surface 75A that protrudes from the outer peripheral surface by a certain height, and a slope 75B that obliquely connects the flat surface to the outer peripheral surface. With this configuration, even if the lock pin 72 contacts the lower cover 61, the movement in the direction returning to the steady position (counterclockwise) is not locked. On the other hand, movement in the direction to move to the operating position (clockwise). Since the lower surface of the front end portion of the lock pin 72 is in contact with the step surface formed on one side (upper side) of the flat surface 75A, the lock pin 72 is limited.

  FIG. 13 is a view showing a part of the protective cover 61, (1) is a rear view, and (2) is a side view. As can be understood from this figure, the latch portions 75 are provided on the outer peripheral surface 61C of the protective cover 61 at regular intervals. The latch portion 75 is manufactured from a synthetic resin integrally with the protective cover 61. In this embodiment, the latch portion 75 is realized in the shape of a protrusion, but may be realized as a recess formed in the outer peripheral surface 61C instead of the protrusion. The lower cover 61 is integrally provided with an operation lever 62 so that the operator can hold the operation lever 62 when the worker arbitrarily opens and closes the lower cover 61.

  As described above, according to the second embodiment, the circular saw device 1 reliably locks the movement of the lower cover that automatically returns to the steady position after a sudden posture change unintended by the operator. So that you can reduce damage to the surrounding crops and materials. Further, even if the lower cover 61 returns to the normal position and the lock mechanism 56 is activated during the return, the lock mechanism 56 does not prevent the lower cover 61 from returning to the normal position. A circular saw device that can reliably prevent damage to crops and materials under any operating conditions can be realized.

  FIG. 14 is a top view of a circular saw apparatus according to the third embodiment of the present invention, and a part thereof is shown in a sectional view. The circular saw device 101 according to the third embodiment is characterized in that a brushless DC motor 102 is used. The brushless DC motor is a DC (direct current) motor without a brush (rectifying brush), has a coil (winding) on the stator 102B side, uses a permanent magnet on the rotor 102A side, and is driven by an inverter circuit. The rotor 102 is rotated by sequentially energizing a predetermined coil. The switching element 106 for turning on and off the energization of the coil of the stator 102B is disposed on a circuit board 105 attached to one end side of the brushless DC motor 102. In order to drive the switching element 106, a control unit (not shown) such as a microcomputer is mounted inside the circular saw device 101.

  FIG. 15 is a block diagram showing the configuration of the drive control system of the brushless DC motor 102. The brushless DC motor 102 is a so-called inner rotor type, and includes a rotor (rotor) 102A configured to include a plurality of sets (two sets in this embodiment) of permanent magnets (magnets) including N poles and S poles. In order to detect the rotational position of the stator 102B composed of three-phase stator windings U, V, and W connected in a star connection and the rotational position of the rotor 102A, the stator 102B is arranged at predetermined intervals, for example, at an angle of 60 °. The three rotational position detecting elements (Hall elements) 121 are provided. Based on the position detection signals from these rotational position detection elements 121, the energization direction and time for the stator windings U, V, W are controlled, and the brushless DC motor 102 rotates. The rotational position detecting element 121 is preferably arranged on the circuit board 105 (see FIG. 14).

  The elements mounted on the drive circuit board 7 include six switching elements 106 (Q1 to Q6) such as FETs (Field Effect Transistors) connected in a three-phase bridge format. The gates of the six switching elements 106 (Q1 to Q6) connected in a bridge are connected to the control signal output circuit 129, and the drains or sources of the six switching elements 106 (Q1 to Q6) are connected in a star connection. Connected to the stator windings U, V, W. As a result, the six switching elements 106 (Q1 to Q6) perform a switching operation according to the switching element drive signals (drive signals such as H4, H5, and H6) input from the control signal output circuit 129, and the inverter circuit 119 Electric power is supplied to the stator windings U, V, and W as three-phase (U-phase, V-phase, and W-phase) voltages Vu, Vv, and Vw as the DC voltage of the applied DC power supply 115. The power source may be an AC power source instead of a DC power source.

  Of the switching element drive signals (three-phase signals) for driving the gates of the six switching elements 106 (Q1 to Q6), three negative power supply side switching elements Q4, Q5, and Q6 are converted to pulse width modulation signals (PWM signals). ) The brushless DC motor is supplied as H4, H5, H6, and the pulse width (duty ratio) of the PWM signal is changed by the control / calculation unit 120 based on the detection signal of the trigger operation amount (stroke) of the trigger switch 127. The power supply amount to 102 is adjusted, and the start / stop of the brushless DC motor 102 and the rotation speed are controlled.

  Here, the PWM signal is supplied to any one of the positive power supply side switching elements Q1 to Q3 or the negative power supply side switching elements Q4 to Q6 of the drive circuit board 7, and the switching elements Q1 to Q3 or the switching elements Q4 to Q6 are operated at high speed. As a result, the power supplied to the stator windings U, V, W from the DC voltage of the DC power supply 115 is controlled by switching. In this embodiment, since the PWM signal is supplied to the negative power supply side switching elements Q4 to Q6, the electric power supplied to each stator winding U, V, W is controlled by controlling the pulse width of the PWM signal. The rotational speed of the brushless DC motor 102 can be controlled by adjusting.

  The circular saw device 101 is provided with speed setting means 128 for setting the rotation speed of the brushless DC motor 102, and the speed instruction circuit 126 controls the rotation speed signal by detecting the setting state of the speed setting means 128. -It transmits to the calculating part 120. Although not shown, the control / arithmetic unit 120 (microcomputer) is a central processing unit (CPU) for outputting a drive signal based on the processing program and data, a ROM for storing the processing program and control data, and data Is configured to include a RAM, a timer, and the like.

  The control / arithmetic unit 120 forms a drive signal for alternately switching the predetermined switching elements 106 (Q1 to Q6) based on the output signals of the rotor position detection circuit 122 and the rotation speed detection circuit 123, and drives the drive signal. The signal is output to the control signal output circuit 129. As a result, the predetermined windings of the stator windings U, V, and W are alternately energized to rotate the rotor 102A in the set rotation direction. In this case, the drive signal applied to the negative power supply side switching elements Q4 to Q6 of the inverter circuit 119 is output as a PWM modulation signal based on the output control signal of the applied voltage setting circuit 125. The current value supplied to the brushless DC motor 102 is measured by the current detection circuit 124, and the value is fed back to the control / arithmetic unit 120 to be adjusted to the set drive power. The PWM signal may be applied to the positive power supply side switching elements Q1 to Q3.

  In this embodiment, the posture change detection circuit 133 that receives an input from the acceleration sensor 131 is provided on the same circuit board as the control / calculation unit 120, and its output is determined by the control / calculation unit 120. That is, it is not necessary to provide a microcomputer for determining the output of the acceleration sensor and controlling the drive of the solenoid as in the first embodiment, and a microcomputer (control / calculation unit 120) for controlling the brushless DC motor 102 is provided. Can be used to control. A control signal is output from the control / calculation unit 120 to the solenoid 20, and the solenoid 20 drives the solenoid pin 21 to lock the lower cover 111.

  According to the third embodiment, when the cutting operation is started and the lower cover 111 comes into contact with the workpiece, the lower cover 112 rotates in accordance with the progress of the cutting operation and is stored in the upper cover 107. (Open state). When the circular saw device 101 undergoes a sudden posture change unintended by the operator, such as when the cutting edge is rebounded from the workpiece by the reaction of the cutting edge biting into the workpiece, an arbitrary position on the upper cover 107, for example, The acceleration sensor 131 disposed at the lower rear end of the cover 107 detects the change in the behavior, and the control / calculation unit 120 determines whether the change exceeds the threshold value. If the change is equal to or greater than the threshold, the solenoid 20 is driven after the waiting time required for the lower cover 111 to return to the steady position (closed state) by the action of the spring, and the solenoid pin 21 is moved to the lower cover 111. It protrudes to a position that hinders the pivoting movement. In this state, even if the lower cover 111 comes into contact with surrounding structures and materials, the lower cover 111 cannot be rotated, so the exposure amount of the blade edge portion does not change. Therefore, the possibility of damaging the structure and material by the blade edge portion does not increase. Thereafter, when the control / calculation unit 120 detects that the trigger switch 127 is turned on, it determines that the cutting operation is to be resumed, and returns the solenoid pin 21 to the steady position.

  Further, the control / calculation unit 120 drives the solenoid 20 and controls the control signal output circuit 129 so that the PWM duty is zero, so that the brushless DC motor 102 can be stopped immediately. In the third embodiment, since the signal processing of the acceleration sensor 131 and the drive control of the solenoid 20 are performed using the control / calculation unit 120 used for the brushless DC motor 102, the increase in the number of parts can be minimized, and the portable The manufacturing cost of the cutting machine can be minimized.

  Further, since the circular saw device 101 has a so-called cutting depth adjusting mechanism that changes the protruding amount of the saw blade 5 from the base bottom surface, the lower cover 111 is adapted to correspond to the cutting depth set by the operator. The waiting time required for the spring to return to the steady position (closed state) is stored in the storage means of the control / calculation unit 120, and a detection means for detecting the depth of cut is provided. Also good. In this case, for example, as shown in FIG. 14, when the adjustment knob 109 constituting the cutting depth adjusting mechanism is loosened to change the amount of projection of the saw blade from the bottom surface of the base 110, the cutting depth is detected in the vicinity of the adjusting knob 109. By providing the means 150 (see FIG. 15), the set cutting depth is detected and a cutting amount signal is output to the control / calculation unit 120. Based on the signal from the cutting depth detection means 150, the control / calculation unit 120 selects the corresponding waiting time from the relationship between the cutting amount stored in the storage means and the waiting time, and sets the waiting time in the timer. Keep it. When the posture change signal (kickback signal) is input from the acceleration sensor 131 to the control / calculation unit 120 via the posture change detection circuit 133, the control / calculation unit 120 activates a timer with a waiting time and cuts it. After the waiting time corresponding to the depth has elapsed, the solenoid 20 is driven to lock the lower cover 111. When the cutting depth is the maximum (FIG. 2), the waiting time is longer than when the cutting depth is the minimum (the amount of protrusion of the saw blade from the base bottom surface is small).

  Furthermore, the acceleration sensor 131 is used to detect the acceleration as a rapid posture change of the circular saw device 101, but the current flowing through the motor and the rotation speed of the motor are detected in addition to or in addition to the acceleration. You may make it do. The current of the motor can be detected by the current detection circuit 124 and the rotation speed of the motor can be detected by the rotation speed detection circuit 123, respectively, and a sudden change in the motor current or the motor rotation speed can be detected to detect a posture change such as kickback. . As shown in FIG. 16, when a so-called kickback occurs in which the cutting edge portion 6 is rebounded from the work piece by a reaction that the blade edge portion 6 is engaged with the work piece at a certain timing during driving of the circular saw device 101, the acceleration is suddenly increased. And the current flowing through the motor 102 (or the current flowing through the inverter circuit 119) also increases rapidly, and the rotational speed of the motor 102 becomes locked and decreases. The occurrence of kickback can be detected by detecting this state with each detection circuit.

  As mentioned above, although demonstrated based on the Example which shows this invention, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the present embodiment, an example using a circular saw device as a portable cutting machine has been described. However, the present invention is not limited to a circular saw device, and the portable cutting machine having a movable protective cover or the like is not limited to this. The invention can be applied as well. Further, although an example using an electric motor as a motor has been described, the present invention can be similarly applied to a portable cutting machine using an air motor or other power motor.

DESCRIPTION OF SYMBOLS 1 Circular saw apparatus 2 Motor 3 Trigger switch 4 Motor housing 4A Handle part 5 Saw blade 6 Blade edge part 7 Upper cover 7A Inner wall 7B (upper cover) Hole 8 Latch part 9 Adjustment lever 10 Base 10A ( Bottom of base 10B Opening 11 of base 11 Lower cover 11A Front end of lower cover 11B Rear end of lower cover 12 Spring 13 Screw 14 Buffer 16 Lock mechanism 17 Screw 18 Substrate 19 Protective case 20 Solenoid 21 Solenoid pin 22 Upper case 22A (Upper case) Projection 23 Lower case 23A, 23B (Lower case) hole 23C (Lower case) Cutout hole 27 Power line 28 Signal line 29 Screw hole 31 Acceleration sensor 32 Microcomputer 32A Storage means 32B Timer 33 Attitude change detection circuit 56 Lock mechanism 61 Lower Bar 61A (lower cover) tip 61B (lower cover) rear end 61 (lower cover) outer peripheral surface 62 operation lever 70 lock member 71 solenoid pin 71A (solenoid pin) through hole 72 lock pin 72A (lock pin) ) Flange 72B Slope 72C (lock pin) Through hole 73 Spring 74 Fixing pin 75 Projection 75A Flat surface 75B (projection) Slope 102 Brushless DC motor 102A Rotor 102B Stator 102C Rotating shaft 102 Housing 104 Handle section 106 Switching element 107 Upper cover 105 Circuit board 106 Switching element 109 Adjustment knob 110 Base 111 Lower cover 112 Cooling fan 115 DC power supply 116 Lock mechanism section 119 Inverter circuit 120 Control / Calculating Unit 121 Rotation Position Detection Element 122 Rotor Position Detection Circuit 123 Rotation Number Detection Circuit 124 Current Detection Circuit 125 Applied Voltage Setting Circuit 126 Speed Instruction Circuit 127 Trigger Switch 128 Speed Setting Unit 129 Control Signal Output Circuit 131 Acceleration Sensor 133 Attitude Change detection circuit 150 Cutting depth detection means

Claims (11)

A motor; cutting means driven by the motor; a housing for housing the motor; a base attached to the housing and slid on a workpiece to be cut by the cutting means; and the base attached to the housing In a portable cutting machine having a closed cover that covers the outer periphery of the cutting means that protrudes downward from and a protective cover that is rotatable in an open state that exposes the outer periphery,
Detecting means for detecting a change in posture of the portable cutting machine;
A portable cutting machine comprising a lock mechanism for restricting movement of the protective cover to the open state after detecting a sudden change in posture of the portable cutting machine during the cutting operation. .   2. The portable cutting machine according to claim 1, wherein after detecting a sudden posture change of the portable cutting machine by the detecting means, the movement of the protective cover is restricted and the motor is stopped. 3. The protective cover is an automatic return type that automatically returns to a steady position and covers the exposed portion of the cutting means when the portable cutting machine is separated from the material to be cut.
The lock mechanism restricts the movement of the protective cover after the protective cover returns to the closed state after detecting a sudden change in posture of the portable cutting machine. Portable cutting machine. The motor is a brushless DC motor, provided with a control means for controlling the rotation of the brushless DC motor,
The portable cutting machine according to any one of claims 1 to 4, wherein the control means controls the operation of the lock mechanism using the output of the detection means.   The portable device according to any one of claims 1 to 5, wherein the detection means sensor is an acceleration sensor provided in the housing and detects a magnitude of acceleration applied to the portable cutting machine. Cutting machine. The portable cutting machine is a portable circular saw device;
The protective cover is a cover that moves in a circumferential direction along the outer periphery of the circular saw blade,
The portable cutting machine according to claim 5, wherein the lock mechanism is provided on an outer peripheral side of a moving range of the protective cover. The lock mechanism has a solenoid and a solenoid pin moved by the solenoid;
The portable cutting machine according to claim 6, wherein the movement of the protective cover is restricted by contacting the protective cover when the solenoid pin moves.   The portable cutting machine according to claim 7, wherein the outer edge of the protective cover is provided with a step portion that allows movement in only one direction of the protective cover when the lock mechanism is operated. Control means for controlling the operation of the locking mechanism;
A protrusion amount changing mechanism for changing the protrusion amount of the cutting means from the bottom surface of the base,
The control means controls the lock mechanism in accordance with the protrusion amount of the cutting means from the bottom surface of the base set by the protrusion amount changing mechanism after detecting the change in posture of the cutting machine by the detection means. The portable cutting machine according to any one of claims 1 to 8, wherein The protrusion amount changing mechanism has a protrusion amount detection means for detecting a protrusion amount of the cutting means from the base,
The portable cutting machine according to claim 9, wherein the control unit controls an operation time of the lock mechanism based on a detection result of the protrusion amount detection unit. Current detecting means for detecting a current flowing through the motor;
A rotational speed detection means for detecting the rotational speed of the motor,
11. The portable device according to claim 4, wherein the control unit controls the lock unit based on a detection signal from at least one of the current detection unit and the rotation speed detection unit. Cutting machine.

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