JP2011000653A - Portable cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable cutter which prevents an operator from making a saw blade contact with a material to be cut so that an impact is applied to the saw blade.SOLUTION: When a detecting member 161 which is provided in a base 14 and urged to protrude in a cutting direction from an outer periphery of the saw blade 11 abuts on the material to be cut, a micro switch 163 abutting on a cam provided in the detecting member 161 is turned on. A control circuit 165 for detecting that the micro switch 163 is turned on interrupts the supply of a current to a motor. Thus, in a state that the detecting member 161 abuts on the material to be cut, even if a motor switch 164 is turned on, the current is not supplied to the motor. Since a load necessary for the operator to move the portable cutter 1 forward is non-linearly changed, the operator easily recognizes that the saw blade 11 is located at a position external near the material to be cut in accordance with the change of the load.

Description

  The present invention relates to a portable cutting machine including a saw blade driven by a motor.

  Conventionally, a portable cutting machine such as a chip saw cutter used for cutting a metal plate or the like has been provided so as to cover the saw blade and the gear cover above the base in order to prevent scattering of dust generated by the cutting operation. A dust collection cover is provided. For this reason, it is difficult for the operator to confirm the position where the outer periphery of the saw blade and the material to be cut are in contact with each other, force the saw blade and the material to be cut into contact with each other, or turn on the motor switch while pressing the saw blade against the material to be cut. Sometimes. In this way, when the saw blade is impacted, if the carbide tip disposed on the outer periphery of the saw blade is broken or dropped, the cutting resistance increases, and as a result, the life of the saw blade is significantly shortened. In order to solve this problem, for example, in the portable electric cutting tool described in Patent Document 1, a notch for confirming a black line (planned cutting line) is provided in the base of the gear cover, and the notch is provided. By providing an illuminating device that irradiates, it is easy for the operator to confirm the end of the material to be cut (the position that first contacts the saw blade) and the black line marked on the material to be cut.

JP 2004-209760 A

  However, in a conventional portable cutting machine, an unfamiliar worker vigorously pushes the portable cutting machine toward the workpiece, or applies a black line marked on the workpiece by applying a saw blade to the workpiece. If the motor is switched on without confirming the saw blade from the material to be cut after confirmation, the saw blade may be shocked.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a portable cutting machine that prevents an operator from impacting the saw blade by vigorously bringing the saw blade into contact with the workpiece. Objective.

In order to achieve the above object, a portable cutting machine according to the first aspect of the present invention comprises:
A motor,
An operable trigger switch;
A base provided below the motor;
A saw blade protruding downward from the base, driven by the motor, and capable of cutting a material to be cut;
Detecting means for detecting a distance between the saw blade and the workpiece;
Determining means for determining whether the distance detected by the detecting means exceeds a predetermined value,
When it is determined by the determination means that the distance detected by the detection means exceeds a predetermined value, when the trigger switch is operated, energization to the motor is not started,
When it is determined by the determination means that the distance detected by the detection means does not exceed a predetermined value, when the trigger switch is operated, energization of the motor is started.
It is characterized by that.

The detection means includes a projecting member projecting downward from the base,
The determination unit may include a micro switch that is turned on by the movement of the protruding member.

  The protruding member may protrude in a cutting direction from a position of the saw blade that contacts the workpiece at the time of cutting.

  The protruding member may be biased in the cutting direction.

  You may further provide the display part which displays whether the said micro switch is an ON state.

In order to achieve the above object, a portable cutting machine according to the second aspect of the present invention comprises:
A motor,
A base provided below the motor;
A saw blade protruding downward from the base, driven by the motor, and capable of cutting a material to be cut;
A movable member movable between a first position protruding in the cutting direction from the saw blade and a second position not protruding in the cutting direction from the saw blade;
Biasing means for biasing the moving member from the second position toward the first position;
The force by which the biasing means biases the moving member increases nonlinearly as the moving member moves from the first position to the second position.
It is characterized by that.

  The moving member may be rotatable between the first position and the second position about an axis provided on a base.

The moving member has a cam portion having the shaft as a rotation center,
The biasing means is
An elastic member that urges the moving member from the second position toward the first position;
While the moving member moves from the first position toward the second position, the moving member comes into contact with the cam portion and biases the moving member from the second position toward the first position. And an urging member to be provided.

  The biasing member may be an elastic member.

  The biasing member may be a damper.

  According to the first aspect of the present invention, cutting is not started while the saw blade is rotated. That is, the cutting can be started by pressing the trigger switch in the state determined by the determining means. For this reason, it can prevent giving a shock to a saw blade from a material to be cut.

  According to the sixth aspect of the present invention, the saw blade does not directly hit the material to be cut while being rotated. That is, the saw blade is brought into contact with the material to be cut while the momentum is reduced by the moving member. For this reason, it can prevent giving an impact to a saw blade.

It is side surface partial sectional drawing of the portable cutting machine which concerns on 1st Embodiment. 5A is a cross-sectional view taken along the line A1-A1 of FIG. 5A when the microswitch is off, and FIG. 5B is a cross-sectional view taken along the line A2-A2 of FIG. 5B when the microswitch is turned on. It is a partial top view of the portable cutting machine which concerns on 1st Embodiment. (A) is a perspective view of the detection member which concerns on 1st Embodiment, (b) is the side view which expanded partially. (A) is a partial cross-sectional view of the side of the detection mechanism when the microswitch is off, and (b) is a partial cross-sectional view of the side of the detection mechanism when the microswitch is on. It is a figure for demonstrating the positional relationship of a to-be-cut material, a saw blade, a detection member, and a pin when the on / off state of a microswitch switches. It is a circuit block diagram of a portable cutting machine. It is a flowchart of an energization control process. It is the BB sectional view of Drawing 10 (a) of the portable cutting machine concerning a 2nd embodiment. (A) is a partial side cross-sectional view of the load mechanism before the cutting operation, and (b) is a partial cross-sectional side view of the load mechanism during the cutting operation. It is a figure showing the relationship between the load which a moving member receives, and a rotation angle. It is side surface partial sectional drawing at the time of using an indicator lamp for the portable cutting machine which concerns on 1st Embodiment. (A) is side surface partial sectional drawing of the load mechanism part at the time of using a damper for the portable cutting machine which concerns on 2nd Embodiment, (b) is CC sectional view taken on the line of (a).

  Hereinafter, the portable cutting machine 1 which concerns on the 1st Embodiment of this invention is demonstrated using drawing. As shown in FIG. 1, the portable cutting machine 1 includes a saw blade 11, a gear cover 12, a saw cover 13, a base 14, a handle portion 15, and a detection mechanism portion 16.

  The saw blade 11 is composed of a disk-shaped steel and a plurality of cemented carbide chips provided on the outer periphery thereof. The saw blade 11 is attached to an output shaft that is rotationally driven by a motor (not shown). A portion of the saw blade 11 protruding from the upper surface of the base 14 is covered with the gear cover 12, and a portion of the portion protruding from the lower surface of the base 14 is covered with the saw cover 13.

  The gear cover 12 houses a gear (not shown) for reducing the rotation of the motor. The gear cover 12 is provided so as to cover the saw blade 11 protruding from the upper surface of the base 14. Furthermore, a dust collection cover (not shown) for collecting dust (chip) generated by the cutting operation is detachably attached to the gear cover 12. Further, as shown in FIGS. 2A and 2B, the gear cover 12 is formed with a cylindrical boss 121 having a guide hole for guiding the rotating shaft 142 that passes through the hinge portion 141. . 2A and 2B, the boss 121 is drawn in a partially cut state in order to make it easier to understand the movement of a pin 167 and a cam portion 161e described later.

  Returning to FIG. 1, the saw cover 13 is provided so as to cover a part of the saw blade 11 protruding from the lower surface of the base 14. The saw cover 13 is rotatable about the output shaft of the motor and is urged in the cutting direction. Therefore, during the cutting operation, the portable cutting machine 1 is pushed forward in the cutting direction, whereby the saw cover 13 is pressed against the material to be cut, and the saw blade 11 is exposed in the direction opposite to the cutting direction against the biasing force. Rotate in the direction. When the cutting operation is completed and the portable cutting machine 1 is separated from the material to be cut, the saw cover 13 is rotated in the cutting direction, that is, so as to cover the saw blade 11 by the urging force.

  The base 14 is formed of a metal plate, and is provided for adjusting the cutting depth of the saw blade 11 and moving the workpiece on the material to be cut to stably perform the cutting operation. As shown in FIG. 3 in an enlarged manner, a groove 14a through which the saw blade 11 passes, a cut material confirmation hole 14b for checking the position of the cut material, and a black line marked on the cut material are confirmed. A black line confirmation hole 14c and a notch 14d are formed. Further, as shown in FIGS. 2A and 2B, the base 14 is located with respect to the gear cover 12 with a pivot shaft 142 passing through a substantially U-shaped hinge portion 141 provided at an end in the cutting direction as a center. And can be pivoted. The cutting depth of the saw blade 11 can be adjusted by the rotation angle of the base 14.

  Returning to FIG. 1, the handle portion 15 is provided on the rear side of the gear cover 12. A motor switch 164 is provided inside the handle portion 15, and the control circuit 165 of the detection mechanism portion 16 and its wiring are housed inside the handle portion 15.

  The detection mechanism unit 16 includes a detection member 161, a return spring 162, a micro switch 163, a motor switch 164, and a control circuit 165.

  As shown in FIG. 4A, the detection member 161 is formed to have a substantially U-shaped cross section by pressing from a metal plate. The detection member 161 has two wing-like plate portions 161 a and 161 b that are positioned in parallel with the saw blade 11 with an appropriate gap. Insertion holes 161c and 161d for inserting the bosses 121 formed in the gear cover 12 are formed at one end of the wing-like plate portions 161a and 161b having the bent portions. As shown in FIGS. 2A and 2B, the detection member 161 is inserted into the insertion holes 161 c and 161 d through the boss 121, and is sandwiched between the hinge portion 141 and the step portion 121 a formed in the boss 121. As described above, the detection member 161 is rotatable around the boss 121 inserted through the insertion holes 161c and 161d, that is, around the rotation shaft 142. Therefore, both the detection member 161 and the gear cover 12 can rotate around the rotation shaft 142.

  As shown in FIG. 4A, a cam portion 161e is formed on the outer peripheral portion of one end portion where the insertion hole 161c of one of the two wing-like plate portions 161a is formed. The cam portion 161e is formed with a smooth arc so that the distance (radius) from the center of the rotation shaft 142 changes. Here, a specific shape of the cam portion 161e will be described with reference to FIG. A point A in FIG. 4 represents a point where a pin 167 and a cam portion 161e, which will be described later, come into contact with each other when the detection member 161 is not in contact with the workpiece. Point B represents a point where the distance between the outer periphery of the cam portion 161e and the center of the rotation shaft 142 is the maximum. From the point A to the point B, the distance between the outer periphery of the cam portion 161e and the center of the rotation shaft 142 gradually increases, and the distance does not change from the point B to the end (the side opposite to the point A).

  Moreover, as shown to Fig.4 (a), the edge parts 161f and 161g which contact the to-be-cut | disconnected material of the wing-like plate parts 161a and 161b are formed in smooth circular arc shape. Thereby, when the detection member 161 is pressed by the material to be cut and moves relative to the portable cutting machine 1 in the direction opposite to the cutting direction, the detection member 161 rotates smoothly.

As shown in FIGS. 2A and 2B, the return spring 162 is formed of a coiled spring, and one end is fixed to the gear cover 12 and the other end is fixed to the detection member 161. The return spring 162 is disposed so as to pass through the boss 121 of the gear cover 12 while being sandwiched between the two wing-like plate portions 161a and 161b of the detection member 161. When the return spring 162 is not compressed by the detection member 161, as shown in FIG. 5A, the wing-like plate portions 161a and 161b of the detection member 161 protrude downward from the base 14, and the edge portions 161f and 161 g is held so as to protrude in the cutting direction from the outer periphery of the saw blade 11.
Further, as shown in FIG. 5B, when the detection member 161 is pressed by the workpiece 3 in the direction opposite to the cutting direction and rotated, the return spring 162 urges the detection member 161 in the cutting direction by an elastic force. To do.

As shown in FIGS. 5A and 5B, the micro switch 163 is housed in the switch holder 166 and is provided above the cam portion 161 e of the detection member 161 inside the gear cover 12. As shown in FIGS. 2A and 2B, the lever 163 a of the micro switch 163 is in contact with the cam portion 161 e via the pin 167.
The pin 167 in contact with the cam portion 161e moves up and down as the detection member 161 rotates, thereby switching the micro switch 163 on and off. Here, the on / off switching of the microswitch 163 will be described with reference to FIG. 6 based on the positional relationship among the material to be cut 3, the saw blade 11, the detection member 161, and the pin 167. In FIG. 6, the solid line indicates the positions of the pin 167 and the detection member 161 in a state where the material 3 to be cut is not in contact with the detection member 161. The dotted lines indicate the positions of the pin 167 and the detection member 161 at the time when the microswitch 163 is switched from off to on or from on to off. The alternate long and short dash line indicates a part of the outer periphery of the saw blade 11 protruding from below the base 14.

First, a case where the microswitch 163 is switched from off to on will be described. When the distance between the outer circumference of the workpiece and the saw blade 11 and x, not in contact with the workpiece 3 and the detection member 161 in the x> x _0, the micro switch 163 is turned off. At x = x ₀ , the detection member 161 and the workpiece 3 come into contact. This state is set as an initial state, and the angle at which the detection member 161 is rotated from the initial state is θ, and the distance that the pin 167 is moved upward is y. When x further decreases, the detection member 161 is pressed by the material 3 to be cut and starts rotating in the direction opposite to the cutting direction. Further, the detection member 161 starts to rotate, and the pin 167 that contacts the cam portion 161e starts to rise.

Furthermore x is reduced, when x = _{x 1,} that is, the rotational angle theta = [Delta] [theta] of the detection member 161, when the movement distance y = [Delta] y of the pin 167, the micro switch 163 is turned on.

  When x further decreases, the tip of the pin 167 reaches a point where the distance from the center of the rotation shaft 142 reaches a maximum value (corresponding to point B in FIG. 4B) at a certain point in time. Ascending of 167 is stopped, and the movement distance y of the pin 167 is not changed while the rotation of the detection member 161 is continued. In this state, since the pin distance y> Δy, the microswitch 163 remains on.

  Next, a case where the microswitch 163 is switched from on to off will be described. When x increases from the position where the microswitch 163 is on, the detection member 161 is rotated in the cutting direction by the elastic force of the return spring 162. Further, as the detection member 161 rotates, the movement distance y is maintained until the tip of the pin 167 reaches the point B in FIG. 4B, but when the point B is exceeded, the movement distance y is increased. It begins to decrease.

When it goes x _{<x 1,} i.e. it becomes theta <[Delta] [theta], becomes the y <[Delta] y, the micro switch 163 is switched from ON to OFF. Then, x further increases and returns to the initial state. As described above, the microswitch 163 is switched on and off depending on whether or not the pin 167 moving with the rotation of the detection member 161 exceeds a predetermined moving distance from the initial state.

  Returning to FIG. 1, the motor switch 164 is provided inside the handle portion 15, and the energization of the motor is switched on and off by the operator's operation.

  The control circuit 165 constantly monitors the on / off state of the microswitch 163 and controls the power supply to the motor according to the state. As shown in FIG. 7, the control circuit 165 includes a control unit 165a, an energization control unit 165b, and a motor switch detection unit 165c.

  The control unit 165a indicates that the energization control unit 165b is energized to the motor 17 based on a signal indicating the on / off state of the micro switch 163 and the on / off state of the switch of the motor 17 from the motor switch detection unit 165c. A signal (energization signal) is transmitted. In addition, when the control unit 165a receives a signal indicating that the switch of the motor 17 is off from the motor switch detection unit 165c, the control unit 165a stops transmitting the energization signal to the energization control unit 165b.

  The energization control unit 165b permits energization of the motor 17 when receiving an energization signal from the control unit 165a. Further, the energization control unit 165b cuts off the energization to the motor 17 when the energization signal is not received from the control unit 165a.

  The motor switch detection unit 165c monitors the on / off state of the motor switch 164 and transmits a signal indicating the state to the control unit 165a.

  Next, the energization control process performed by the control unit 165a will be described with reference to FIG.

  The control unit 165a starts the energization control process when the portable cutting machine 1 is connected to the power source 4. As the power source 4, for example, a charger detachably provided on the portable cutting machine 1 may be used, or an AC power source for supplying DC power to the portable cutting machine 1 via a converter. May be used.

  The control unit 165a determines whether or not the micro switch 163 is on based on the signal from the micro switch 163 (step S11).

  When it is determined that the micro switch 163 is on (that is, the saw blade 11 and the workpiece 3 are in contact or very close to each other) (step S11; Yes), the controller 165a turns off the micro switch 163. Wait until it becomes.

  When it is determined that the micro switch 163 is not on (that is, the saw blade 11 and the workpiece 3 are separated) (step S11; No), the control unit 165a is based on the signal from the motor switch detection unit 165c. It is determined whether or not the motor switch 164 is on (step S12).

  When it is determined that the motor switch 164 is not on (step S12; No), the control unit 165a returns to the process of step S11.

  If it is determined that the motor switch 164 is on (step S12; Yes), the control unit 165a starts transmitting an energization signal to the energization control unit 165b (step S13).

  Next, the control unit 165a determines whether or not the motor switch 164 is off based on the signal from the motor switch detection unit 165c (step S14).

  When it is determined that the motor switch 164 is not off (step S14; No), the control unit 165a waits until the motor switch 164 is turned off.

  When it is determined that the motor switch 164 is off (step S14; Yes), the control unit 165a stops transmitting the energization signal to the energization control unit 165b (step S15). And the control part 165a returns to step S11, and repeats the above process. Note that the energization control process ends when the power supply to the portable cutting machine 1 is cut off.

  Thus, when the micro switch 163 is on, the control unit 165a does not transmit an energization signal to the energization control unit 165b even when the motor switch 164 is turned on by an operator. Accordingly, since the energization control unit 165b cuts off the energization to the motor 17, the motor 17 is not driven. Further, when the micro switch 163 is off, when the motor switch 164 is turned on by the operator, the control unit 165a transmits an energization signal to the energization control unit 165b. Accordingly, the energization control unit 165b permits energization of the motor 17, and thus the motor 17 is driven. Further, when the micro switch 163 is turned on after the motor 17 is driven, the control unit 165a continues to transmit an energization signal. Therefore, since the energization control unit 165b permits energization to the motor 17, the motor 17 continues to be driven. When the motor switch 164 is turned off, the control unit 165a stops transmitting the energization signal to the energization control unit 165b. Therefore, the energization control unit 165b enters a state where the energization to the motor 17 is interrupted.

When an operator performs a cutting operation using the portable cutting machine 1 configured as described above, first, the operator places the base 14 on the workpiece 3, and the black line marked on the workpiece 3 The cutting position is confirmed by the notch portion 14d of the base 14 and the black line confirmation hole 14c. Next, the operator turns on the motor switch 164 and pushes the portable cutting machine 1 in the cutting direction while rotating the saw blade 11 to perform the cutting operation. Here, contact between the saw blade 11 and the workpiece 3, or if the operator in a state in which apart x ₁ following distance 6 turns on the motor switch 164, and the saw blade 11 and the workpiece The operation of the portable cutting machine 1 when the operator turns on the motor switch 164 in a state where 3 is separated from x1 will be described.

First, the saw blade 11 and the workpiece 3 is contacted, or x operator ₁ in a state in which are separated by a distance of less than a description will be given of the operation of the portable cutting tool 1 in the case of turning on the motor switch 164. Saw blade 11 and the workpiece 3 and the contact, or in the state where x ₁ are separated by a distance of less than the detection member 161 is pressed from the workpiece 3, the cutting direction against the elastic force of the return spring 162 It is the state rotated in the opposite direction. Further, the pin 167 in contact with the cam portion 161e rises with the rotation of the cam portion 161e, and the movement distance y is equal to or greater than Δy, so that the microswitch 163 is in an on state. At this time, the control unit 165a of the control circuit 165 determines that the microswitch 163 is on. Therefore, even if the operator turns on the motor switch 164, the control unit 165a causes the energization control unit 165b to cut off the energization of the motor 17, so the motor 17 is not driven.

Next, the saw blade 11 and the workpiece 3 by the operator in a state where apart than x ₁ is the operation of the portable cutting tool 1 in the case of turning on the motor switch 164. In a state where the saw blade 11 and the workpiece 3 are separated by more than x _1, the rotation angle theta <[Delta] [theta] of the detection member 161, because it is a moving distance y <[Delta] y of the pin 167, the micro switch 163 is off State. At this time, the control unit 165a of the control circuit 165 determines that the microswitch 163 is off. Therefore, when the operator turns on the motor switch 164, the control unit 165a allows the energization control unit 165b to permit energization of the motor 17, and thus the motor 17 is driven.

  Thus, even if the operator turns on the motor switch 164 in a state where the saw blade 11 is in contact with the workpiece 3 or in a very close position, the state is detected by the detection mechanism unit 16. Thus, the motor 17 is controlled so as not to be energized, so that it is possible to prevent the saw blade 11 from being given an impact.

  Next, a second embodiment of the present invention will be described with reference to the drawings. The portable cutting machine 2 according to the present embodiment is different in that it includes a load mechanism unit 26 described later instead of the detection mechanism unit 16 in the first embodiment, and the other components are the same. For this reason, similar constituent elements are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 9, the load mechanism unit 26 includes a moving member 261, a return spring 162, a pin 267, and a load spring 268. Note that the moving member 261 has the same position and shape as the detection member 161 in the first embodiment, and thus the description thereof is omitted.

  As shown in FIGS. 10A and 10B, the pin 267 is provided above the moving member 261 inside the gear cover 12 so as to contact the cam portion 261e. Further, the pin 267 is provided with a flange portion 267a, and a portion below the flange portion 267a is inserted through a hole formed in the gear cover 12, and the tip portion is in contact with the cam portion 261e. A portion above the flange portion 267 a of the pin 267 is inserted into the load spring 268.

  The load spring 268 is formed of a coiled spring and is provided so as to accommodate a portion above the flange portion 267 a of the pin 267 provided in the gear cover 12.

  When an operator performs a cutting operation using the portable cutting machine 2 configured as described above, the operator first places the base 14 on the workpiece 3, and the black line marked on the workpiece 3 The cutting position is confirmed by the notch 14d of the base and the black line confirmation hole 14c. Next, the operator turns on the motor switch 164 and pushes the portable cutting machine 2 in the cutting direction while rotating the saw blade 11 to perform the cutting work. Here, the operation of the portable cutting machine 2 when the operator pushes the portable cutting machine 2 will be described.

  Since the moving member 261 protrudes in the cutting direction from the saw blade 11, when the portable cutting machine 2 is pushed in the cutting direction, the moving member 261 contacts the member to be cut 3 before the saw blade 11. Here, the load applied to the portable cutting machine 2 by the operator before the moving member 261 contacts the workpiece 3 is portable against the frictional force between the portable cutting machine 2 and the workpiece 3. This is a load necessary to push the cutting machine 2 forward.

After the moving member 261 and the material to be cut 3 come into contact with each other, the moving member 261 is pressed and rotated by the material to be cut 3 in the direction opposite to the cutting direction, and at the same time, the pin 267 that contacts the cam portion 261e is raised. At this time, the moving member 261 moves against the return spring 162 and the load spring 268. Therefore, in order for the operator to push the portable cutting machine 2 forward, it is necessary to apply a load for pushing the portable cutting machine 2 against the elastic force of these springs in addition to the frictional force described above. . FIG. 11 shows the relationship between the rotation angle θ of the moving member 261 and the load F received by the moving member 261 at this time. In FIG. 11, a chain line represents a load applied to the moving member 261 by the load spring 268, a one-dot chain line represents a load applied to the moving member 261 by the return spring 162, and a solid line represents a combined load that is the sum of loads by these springs. When the rotation angle θ <θ ₁ (θ ₁ is the rotation angle at the point B in FIG. 4B), the load is increased as the rotation angle θ increases, that is, the portable cutting machine 2 is cut in the cutting direction. Increases linearly as it is pushed forward. However, the rotation angle theta> theta _1, since the distance between the center point and the pivot shaft 142 abuts the cam portion 261e of the pin 267 does not change, does not change the height of the pin 267. Therefore, the elastic force by the load spring 268 is constant as shown in FIG. On the other hand, the rate of increase in load by the return spring 162 does not change. Therefore, the increase rate of the combined load changes at the rotation angle θ = θ ₁ and increases nonlinearly as a whole. When the cutting operation is completed and the saw blade 11 is moved away from the material 3 to be cut, the moving member 261 rotates in the cutting direction by the elastic force of the return spring 162 while being in contact with the material 3 to be cut, and accordingly the pin is moved. 267 maintains its height until reaching point B in FIG. 4B, and after reaching point B, its height decreases. Finally, the state before the contact with the workpiece 3 is restored.

  In this way, when the operator pushes the portable cutting machine 2 toward the workpiece 3, the workpiece 3 comes into contact with and pushes the moving member 261 that protrudes in the cutting direction from the saw blade 11 and is biased. This increases the load required. Therefore, even when the operator vigorously pushes the saw blade 11 toward the workpiece 3, the momentum can be reduced and the impact applied to the saw blade 11 can be reduced. Moreover, the operator can easily know that the distance between the saw blade 11 and the workpiece 3 is very close due to a change in the load necessary to push the portable cutting machine 2 forward.

In addition, as shown in FIG. 11, at the time of cutting work, an operator needs to apply a load (composite load) for pushing the portable cutting machine 2 against the elastic force of the return spring 162 and the load spring 268. is there. Here, the return spring 162 only needs to have an elastic force to return the moving member 261 to the original position after the work is completed. Then, the load for pushing the portable cutting machine 2 after the moving member 261 contacts the workpiece 3 can be adjusted by the elastic force of the load spring 268. Further, the rotation angle theta> theta _1, also the moving member 261 is rotated without increasing the load by the load spring 268 is constant. Therefore, the use of the return spring 162 and the load spring 268, as compared with the case of using only the return spring which gives the same amount of load and combined load at the pivot angle theta <theta ₁ to the moving member 261, during the cutting operation Since the necessary load is small, workability is good.

  In addition, this invention is not limited to said embodiment, A various deformation | transformation and application are possible.

  In the first embodiment of the present invention, even when the motor switch 164 is turned on when the detection mechanism 16 detects that the saw blade 11 and the workpiece 3 are in contact with each other or in a very close position, the motor 17 is turned on. However, as shown in FIG. 12, an indicator lamp 18 that is turned on / off by turning on / off the micro switch 163 provided in the detection mechanism unit 16 may be further provided. . Also in the second embodiment, the micro switch 163 in the first embodiment may be provided in the same manner, and an indicator lamp that is turned on / off by turning on / off the micro switch 163 may be further provided. Thus, the operator can easily know visually that the saw blade and the material to be cut are in contact with or very close to each other. Further, a buzzer or the like that emits a sound when the microswitch 163 is turned on may be provided. As a result, the operator can easily know by hearing that the saw blade and the material to be cut are in contact with or very close to each other.

  Further, in the second embodiment of the present invention, by using the cam portion 261e of the moving member 261 and the load spring 268 that contacts the cam portion 261e via the pin 267, it corresponds to the combined load shown in FIG. In this configuration, a nonlinear urging force is applied to the moving member 261. However, a damper 269 may be used as shown in FIGS. 13A and 13B instead of the pin 267 and the load spring 268. Thereby, compared with the case where the load spring 268 is used, the load required during the cutting operation can be reduced, and the workability is good.

  In the second embodiment of the present invention, the case where the shape of the cam portion 261e of the moving member 261 is specifically the shape shown in FIG. 4B has been described. Also good. For example, in FIG. 4B, the outer periphery in the counterclockwise direction from the point B is formed so as to have a constant radius, but may be formed so that the radius is smaller than the point B. . Thus, after the point where the pin 267 and the cam portion 261e of the moving member 261 contact each other exceeds the point B, the radius becomes small and the pin 267 descends due to the elastic force of the load spring 268, so that the load spring 268 extends. Thus, the elastic force applied to the moving member 261 is reduced. Therefore, the load required by the operator during the cutting operation can be smaller than that in the case of using the moving member 261 in which the radius of the outer periphery in the counterclockwise direction from the point B is constant, so that the workability is good.

  In the first and second embodiments of the present invention, the portable cutting machines 1 and 2 have been described as having the disk-shaped saw blade 11 that is rotationally driven by a motor. For example, a portable cutting machine having a saw blade that strokes up and down by a motor such as a jigsaw may be used.

DESCRIPTION OF SYMBOLS 1, 2 Portable cutting machine 11 Saw blade 12 Gear cover 121 Boss 121a Step part 13 Saw cover 14 Base 14a Groove 14b Material to be cut 14c Black wire confirmation hole 14d Notch part 141 Hinge part 142 Rotating shaft 15 Handle part 16 Detection mechanism part 161 Detection members 161a and 161b Feather plate portions 161c and 161d Insertion holes 161e Cam portions 161f and 161g Edge 162 Return spring 163 Micro switch 163a Lever 164 Motor switch 165 Control circuit 165a Control unit 165b Energization control unit 165c Motor switch detection unit 166 Switch holder 167 Pin 17 Motor 18 Indicator light 26 Load mechanism 261 Moving member 267 Pin 268 Load spring 269 Damper 3 Cut material 4 Power supply

Claims (10)

A motor,
An operable trigger switch;
A base provided below the motor;
A saw blade protruding downward from the base, driven by the motor, and capable of cutting a material to be cut;
Detecting means for detecting a distance between the saw blade and the workpiece;
Determining means for determining whether the distance detected by the detecting means exceeds a predetermined value,
When it is determined by the determination means that the distance detected by the detection means exceeds a predetermined value, when the trigger switch is operated, energization to the motor is not started,
When it is determined by the determination means that the distance detected by the detection means does not exceed a predetermined value, when the trigger switch is operated, energization of the motor is started.
A portable cutting machine characterized by that. The detection means includes a projecting member projecting downward from the base,
The determination means includes a microswitch that is turned on by the movement of the protruding member.
The portable cutting machine according to claim 1. The protruding member protrudes in the cutting direction from the position of the saw blade that contacts the workpiece at the time of cutting,
The portable cutting machine according to claim 2, wherein: The protruding member is biased in the cutting direction;
The portable cutting machine according to any one of claims 1 to 3, wherein: A display unit for displaying whether or not the microswitch is in an ON state;
The portable cutting machine according to any one of claims 1 to 4, wherein the portable cutting machine is characterized in that: A motor,
A base provided below the motor;
A saw blade protruding downward from the base, driven by the motor, and capable of cutting a material to be cut;
A movable member movable between a first position protruding in the cutting direction from the saw blade and a second position not protruding in the cutting direction from the saw blade;
Biasing means for biasing the moving member from the second position toward the first position;
The force by which the biasing means biases the moving member increases nonlinearly as the moving member moves from the first position to the second position.
A portable cutting machine characterized by that. The moving member is rotatable between the first position and the second position about an axis provided on a base.
The portable cutting machine according to claim 6. The moving member has a cam portion having the shaft as a rotation center,
The biasing means is
An elastic member that urges the moving member from the second position toward the first position;
While the moving member moves from the first position toward the second position, the moving member comes into contact with the cam portion and biases the moving member from the second position toward the first position. An urging member to be provided,
The portable cutting machine according to claim 6 or 7, characterized by the above. The biasing member is an elastic member.
The portable cutting machine according to claim 8, wherein: The biasing member is a damper;
The portable cutting machine according to claim 8, wherein:

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