A safety interlock device for a power saw

Abstract

The present invention discloses a safety interlock device for a power saw, comprising: a downward pressing and locking mechanism, a motor start button, and a head locking mechanism; the downward pressing and locking mechanism is as follows: a swing rod, a downward pressing flap, and an unlocking block are provided on the head housing, the middle parts of the swing rod and the downward pressing flap are respectively hinged to the head housing, the inner end of the downward pressing flap is lifted upward under the action of a torsion spring, the front end of the swing rod is located above the inner end of the downward pressing flap, the rear end of the swing rod is fixed to the unlocking block, and a return spring is provided above the rear end of the swing rod; the head locking mechanism is as follows: a locking piece is hinged on a mounting bracket, a locking groove is provided at the front end of the locking piece, a rotating shaft, a locking pin, and a driving member are provided on the head housing, a sloping convex platform is provided at the inner end of the rotating shaft, and the outer end of the rotating shaft is fixed to the driving member; a connecting rod fixed to the motor start button is provided on the head housing, a blocking convex platform is provided on the rear part of the swing rod, a hook groove is provided on the connecting rod, and a hook platform is provided on the rotating shaft. The above device can improve the safety of the power saw and facilitate the replacement of the saw blade.

Description

Technical Field

[0001] The present invention relates to the field of power tools, and particularly to a safety interlock device for a saw. Background Art

[0002] The structure of the existing saw includes: a base plate for pressing an object to be sawed during cutting, a mounting frame, and a machine head with a saw blade mounted thereon. The saw blade is driven to rotate by a motor in the machine head. The mounting frame is mounted on the base plate, and the rear end of the machine head is hinged to the mounting frame, so that the machine head can swing up and down on the mounting frame. A compression spring is provided between the machine head and the mounting frame to push the machine head upward and reset the machine head upward. After the machine head is reset upward and abuts against the limit backstop on the mounting frame, the saw blade can be located above the base plate. Pressing the machine head downward causes the machine head to overcome the elastic force of the compression spring and drive the saw blade to swing downward, and then the saw blade can extend downward out of the base plate. The saw blade can cut the object to be sawed only after extending downward out of the base plate and being driven to rotate by the motor. In addition, when the saw blade needs to be replaced, the machine head also needs to be pressed downward to make the machine head swing downward against the elastic force of the compression spring until the mounting screw of the saw blade exposes from the notch on the mounting frame at the saw blade replacement position. A downward pressing locking mechanism that can only be pressed downward after being unlocked is provided on the machine head, and a motor start button that can start the motor after being pressed and reset by a spring. A power supply is provided in the machine head, and the power supply supplies power to the motor through a power supply circuit. After the motor start button is pressed, the motor is powered on and starts to drive the saw blade to rotate. However, the downward pressing locking mechanism and the motor start button on the existing saw are independent of each other and not interlocked, so that the motor start button can be pressed to drive the saw blade to rotate without unlocking the downward pressing locking mechanism, which will pose a great safety hazard. In addition, during the entire saw blade replacement process, the worker needs to always press the machine head to keep the machine head at the saw blade replacement position. Since one hand of the worker needs to press the machine head, the worker can only replace the saw blade with the other hand, which makes the saw blade replacement extremely inconvenient and increases the labor intensity of the worker. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a safety interlock device for a saw that can improve the safety of the saw.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: A safety interlock device for a saw, comprising: a mounting bracket mounted on a bottom plate, a machine head hinged to the mounting bracket, a downward pressing locking mechanism provided on the machine head, and a motor start button reset by a button spring. It is characterized in that: it further comprises: a machine head locking mechanism, when the machine head is pressed down and swings downward to the saw blade replacement position, the machine head locking mechanism can lock the machine head for saw blade replacement; the structure of the downward pressing locking mechanism is: a swing rod running in the front-rear direction, a downward pressing flap running in the left-right direction, and an unlocking block are provided on the machine head housing. The middle parts of the swing rod and the downward pressing flap are respectively hinged to the machine head housing. The inner end of the downward pressing flap is lifted upward under the action of a flap torsion spring provided in the machine head, so that the outer end of the downward pressing flap is pressed downward to a position where it can abut against a blocking block on the mounting bracket to prevent the machine head from swinging downward. At this time, the downward pressing locking mechanism is in a locked state. The front end of the swing rod is located above the inner end of the downward pressing flap, and the rear end of the swing rod is fixed to the unlocking block. By driving the unlocking block to move upward, the front end of the swing rod can swing downward to press the inner end of the downward pressing flap, so that the outer end of the downward pressing flap can be lifted upward to a position where it does not prevent the machine head from swinging downward. At this time, the downward pressing locking mechanism is in an unlocked state. A reset spring is provided above the rear end of the swing rod between the swing rod and the machine head housing, which can press the rear end of the swing rod downward to reset the unlocking block downward; the structure of the machine head locking mechanism is: a lock piece is provided on the mounting bracket on the side of the machine head. The rear end of the lock piece is hinged to the mounting bracket, so that the lock piece can swing up and down. An upward-opening lock groove is provided at the front end of the lock piece. The lock piece swings upward under the action of a lock piece torsion spring provided on the mounting bracket until its front end abuts against a limit bar on the mounting bracket. A rotatable shaft running in the left-right direction, a lock pin reset by a lock pin spring running in the left-right direction, and a driving member are provided on the machine head housing. The inner end of the lock pin is arranged opposite to the inner end of the shaft, and the outer end of the lock pin faces the side where the lock piece is located. A ramped boss for pressing the lock pin is provided at the inner end of the shaft. The outer end of the shaft is fixed to the driving member, so that the shaft can be driven to rotate through the driving member. After the shaft is driven to rotate forward through the driving member, the ramped boss can gradually press the lock pin outward through the slope surface, so that the outer end of the lock pin can extend outward to the working position. The outer end of the lock pin in the working position can press the lock piece when the machine head swings downward, so that the lock piece can swing downward, so that the outer end of the lock pin can swing downward along the upper side of the lock piece. When the machine head swings downward to the saw blade replacement position, the outer end of the lock pin just moves above the lock groove. At this time, the lock piece will rotate upward and reset under the action of the lock piece torsion spring, so that the outer end of the lock pin is caught in the lock groove, so that the lock piece can lock the machine head. At this time, the machine head locking mechanism is in a locked state. When unlocking is required, after the shaft is driven to rotate reversely through the driving member, the ramped boss will gradually release the pressing on the lock pin, so that the lock pin can retract under the action of the lock pin spring and disengage from the lock piece, so that the machine head locking mechanism can be in an unlocked state;A connecting rod that runs horizontally and can slide back and forth is also provided on the head housing. Both the connecting rod and the rotating shaft are located below the swing rod, and the rotating shaft is in front of the connecting rod. The connecting rod is fixed to the motor start button, so that the connecting rod can move backward as the motor start button is pressed. A blocking boss is provided on the side wall at the rear of the swing rod. When the pressing and locking mechanism is in the locked state, the blocking boss is located behind the connecting rod and can block the backward movement of the connecting rod, preventing the connecting rod from moving backward and thus preventing the motor start button from being pressed. When the pressing and locking mechanism is in the unlocked state, the blocking boss will swing upward with the rear end of the swing rod and will not block behind the connecting rod, allowing the motor start button to be pressed to start the motor. A hook groove with an open bottom is provided at the front end of the connecting rod, and a hook platform is provided on the rotating shaft. When the motor start button is not pressed, the hook platform can rotate upward and hook into the hook groove as the rotating shaft rotates forward, thereby being able to abut against the front side wall of the hook groove, preventing the connecting rod from moving backward and preventing the motor start button from being pressed. After the motor start button is pressed, the bottom wall at the front end of the connecting rod will move backward to a position where it blocks the forward rotation of the blocking hook platform, preventing the hook platform from rotating forward and thus preventing the rotating shaft from rotating forward, so that the locking pin cannot extend to the working position.

[0005] Further, in the above-mentioned safety interlock device for a saw, the driving member is a handle. The lower end of the handle is fixed to the outer end of the rotating shaft. After the driving handle swings forward, the rotating shaft can rotate forward, and after the driving handle swings backward, the rotating shaft can rotate backward. On the head housing, there are also a front limiting convex edge for the forward-swinging handle to abut against for front limiting of the handle and a rear limiting convex edge for the backward-swinging handle to abut against for rear limiting of the handle.

[0006] Further, in the above-mentioned safety interlock device for a saw, a clamping platform is provided at the outer end of the rotating shaft, and a clamping groove is provided on the inner side of the lower end of the handle. The lower end of the handle and the rotating shaft are locked and fixed by screws, and when fixed, the clamping platform is clamped into the clamping groove, so that the handle can drive the rotating shaft to rotate through the cooperating clamping platform and clamping groove.

[0007] Further, in the above-mentioned safety interlock device of a power saw, the following is provided: on the surface of the head housing opposite to the inner side wall of the handle, there are two elastic piece holes arranged front and back. In each of the two elastic piece holes, there is an elastic piece with one end fixed to the head housing and the other end unfixed. On the outer surface of the unfixed ends of the two elastic pieces, there is a positioning boss protruding outward from the surface of the head housing. The two positioning bosses are respectively a front positioning boss and a rear positioning boss. On the inner side wall of the handle, there is a front positioning hole and a rear positioning hole. When the handle swings back and forth, its inner side wall can respectively squeeze the two positioning bosses. When the positioning bosses are squeezed, the elastic piece where they are located will elastically deform inward, so that the two positioning bosses can move inward and abut against the inner side wall of the handle; when the handle swings forward to abut against the front limit convex edge, the front positioning boss can just be inserted into the front positioning hole to perform front positioning on the handle; when the handle swings backward to abut against the rear limit convex edge, the rear positioning boss can just be inserted into the rear positioning hole to perform rear positioning on the handle.

[0008] Further, in the above-mentioned safety interlock device of a power saw, the following is provided: above the handle, there is a U-shaped frame straddling the head housing, and one side of the U-shaped frame is fixed to the upper end of the handle.

[0009] Further, in the above-mentioned safety interlock device of a power saw, the hook groove is an arc-shaped hook groove, and the hook platform is an arc-shaped hook platform.

[0010] The advantages of the present invention are as follows: in the safety interlock device of the power saw, a head locking mechanism is added, so that when the head swings downward to the saw blade replacement position, it can be locked by the head locking mechanism. Therefore, when replacing the saw blade, the head can be kept in the saw blade replacement position without manual pressing of the head, which facilitates the replacement of the saw blade; in addition, there is the following interlock relationship among the downward pressure locking mechanism, the motor start button, and the head locking mechanism in the safety interlock device: (1) Only when the downward pressure locking mechanism is in the unlocked state and the hook platform on the rotating shaft in the head locking mechanism is not hooked into the hook groove, the motor start button can be pressed; (2) When the motor start button is pressed, the rotating shaft cannot rotate forward, so that the locking pin in the head locking mechanism cannot extend to the working position, and thus the head locking mechanism cannot lock the head at the saw blade replacement position. The above interlock relationship can greatly improve the safety performance of the power saw. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective three-dimensional structure diagram of one perspective of the power saw of the present invention.

[0012] Figure 2 It is a perspective three-dimensional structure diagram of another perspective of the power saw of the present invention.

[0013] Figure 3Schematic three-dimensional structure diagram of the state when the saw blade of the electric saw of the present invention is replaced.

[0014] Figure 4 Schematic three-dimensional structure diagram of the head of the present invention after removing one side housing and the handle.

[0015] Figure 5 Schematic three-dimensional structure diagram of the electric saw of the present invention after removing the head.

[0016] Figure 6 Schematic structure diagram of the positions of relevant parts when the handle of the present invention does not swing forward and the motor start button is not pressed.

[0017] Figure 7 Schematic structure diagram of the positions of relevant parts when the handle of the present invention swings forward and the motor start button is not pressed.

[0018] Figure 8 is Figure 1 Schematic structure diagram of the handle shown in

[0019] Figure 9 is Figure 1 Schematic structure diagram of the partial housing on the head that cooperates with the handle shown in Detailed implementation manners

[0020] The present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0021] Such as Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7As shown, a safety interlock device of an electric saw comprises: a mounting frame 9 mounted on a bottom plate, a machine head 1 hinged to the mounting frame 9, a push-down locking mechanism arranged on the machine head 1, and a motor start button 3 reset by a button spring, the button spring for resetting the motor start button 3 being arranged between the motor start button 3 and the machine head housing, and the button spring being compressed when the motor start button 3 is pressed; and further comprising: a machine head locking mechanism, when the machine head 1 is pressed down and swung downward to a saw blade replacement position, the machine head locking mechanism can lock the machine head 1 for replacing the saw blade; the structure of the push-down locking mechanism is: a swing rod 21 extending forward and backward is arranged on the housing of the machine head 1, The locking mechanism 21 is in a locked state, and the front end of the swing rod 21 is located above the inner end of the locking plate 22, and the rear end of the swing rod 21 is fixed to the unlocking block 2. By driving the unlocking block 2 to move upward, the front end of the swing rod 21 can be swung downward to press the inner end of the locking plate 22, so that the locking mechanism 21 is locked. The outer end of the pressure blocking piece 22 can be tilted upward to a position where it does not prevent the machine head 1 from swinging downward. At this time, the downward locking mechanism is in an unlocked state. A return spring 23 is arranged above the rear end of the swing rod 21 and is located between the swing rod 21 and the housing of the machine head 1. The return spring 23 can press the rear end of the swing rod 21 downward to reset the unlocking block 2 downward; the structure of the machine head locking mechanism is as follows: a locking piece 43 is arranged on the mounting frame 9 and is located on the side of the machine head 1. The rear end of the locking piece 43 is hinged to the mounting frame 9 so that the locking piece 43 can swing up and down. A locking groove 431 with an opening facing upward is arranged on the front end of the locking piece 43. The locking piece 43 swings upward to its position under the action of the locking piece torsion spring arranged on the mounting frame 9. The front end is against the limit stopper bar on the mounting frame 9, and a rotatable shaft 41 extending left and right, a lock pin 42 extending left and right and reset by a lock pin spring, and a driving member 4 are arranged on the housing of the machine head 1. The lock pin spring for resetting the lock pin 42 is located between the lock pin 42 and the housing of the machine head 1, and the lock pin spring will be compressed when the lock pin 42 is pressed outward; the inner end of the lock pin 42 is arranged opposite to the inner end of the shaft 41, and the outer end of the lock pin 42 faces the side where the lock plate 43 is located. A sloped boss 411 that can press the lock pin 42 is arranged on the inner end of the shaft 41, and the outer end of the shaft 41 is fixed to the driving member 4, so that the shaft 41 can be driven to rotate by the driving member 4;Moreover, after the driving member 4 drives the rotating shaft 41 to rotate forward, the slope-shaped boss 411 can gradually press the locking pin 42 outward through the slope surface, so that the outer end of the locking pin 42 can extend outward to the working position. When the head 1 swings downward, the outer end of the locking pin 42 at the working position can press the locking piece 43, so that the locking piece 43 can swing downward. Thus, the outer end of the locking pin 42 can swing downward while abuting against the upper side surface of the locking piece 43. When the head 1 swings downward to the position for replacing the saw blade, the outer end of the locking pin 42 just moves above the locking groove 431. At this time, the locking piece 43 will rotate upward and reset under the action of the locking piece torsion spring, so that the outer end of the locking pin 42 is caught in the locking groove 431, thereby enabling the locking piece 43 to lock the head 1. At this time, the head locking mechanism is in the locked state. When unlocking is required, after the driving member 4 drives the rotating shaft 41 to rotate reversely, the slope-shaped boss 411 will gradually release the pressing on the locking pin 42, so that the locking pin 42 can retract under the action of the locking pin spring and disengage from the locking piece 43, thereby enabling the head locking mechanism to be in the unlocked state.;

[0022] The reason why the outer end of the locking pin 42 at the working position can press the locking piece 43 when swinging downward is as follows: The movement trajectory of the locking groove 431 is on a small circle with the hinge point of the locking piece 43 as the center, and the movement trajectory of the locking pin 42 is on a large circle with the hinge point of the head 1 as the center. The small circle corresponding to the locking groove 431 and the large circle corresponding to the locking pin 42 intersect at two points, and the center of the small circle is located inside the large circle; The reason why the outer end of the locking pin 42 can be caught in the locking groove 431 is that there is an intersection between the two circles, so that the outer end of the locking pin 42 and the locking groove 431 can be caught at the intersection of the two circles; The reason why the locking piece 43 can lock the head 1 after the outer end of the locking pin 42 is caught in the locking groove 431 is that the centers of the movement trajectories of the locking pin 42 and the locking groove 431 are not the same. After the locking groove 431 and the locking pin 42 are caught, they will limit each other whether swinging upward or downward. Thus, the locking pin 42 and the locking groove 431 will be limited at the caught position and cannot swing, thereby enabling the locking piece 43 to lock the head 1.

[0023] On the housing of the machine head 1, there is also a connecting rod 31 arranged in the front-back direction and capable of sliding back and forth. Both the connecting rod 31 and the rotating shaft 41 are located below the swing rod 21, and the rotating shaft 41 is located in front of the connecting rod 31. The connecting rod 31 is fixed to the motor start button 3, so that the connecting rod 31 can move backward as the motor start button 3 is pressed. On the side wall at the rear of the swing rod 21, there is a blocking boss 24. When the downward pressing locking mechanism is in the locked state, the blocking boss 24 is located behind the connecting rod 31 and can block the backward movement of the connecting rod 31, making the connecting rod 31 unable to move backward and preventing the motor start button 3 from being pressed. When the downward pressing locking mechanism is in the unlocked state, the blocking boss 24 will swing upward with the rear end of the swing rod 21 and will not block behind the connecting rod 31, so that the motor start button 3 can be pressed to start the motor. On the front end of the connecting rod 31, there is a hook groove 32 with an open bottom, and on the rotating shaft, there is a hook platform 44. In this embodiment, the hook groove 32 is an arc-shaped hook groove, and the hook platform 44 is an arc-shaped hook platform; when the motor start button 3 is not pressed, the hook platform 44 can rotate upward and hook into the hook groove 32 as the rotating shaft 41 rotates forward, so as to be able to abut against the front side wall of the hook groove 32, making the connecting rod 31 unable to move backward and preventing the motor start button 3 from being pressed; when the motor start button 3 is pressed, the bottom wall at the front end of the connecting rod 31 will move backward to a position where it blocks the forward rotation of the blocking hook platform 44, making the hook platform 44 unable to rotate forward and preventing the rotating shaft 41 from rotating forward, so that the locking pin 42 cannot extend to the working position.

[0024] As described above, after the downward pressing locking mechanism is in the unlocked state, the machine head can be pressed downward and swing; after the motor start button is pressed, the saw blade on the machine head will rotate; after the locking pin in the machine head locking mechanism extends to the working position, the machine head can be locked at the saw blade replacement position.

[0025] There is the following interlock relationship among the downward pressing locking mechanism, the motor start button, and the machine head locking mechanism: (1) Only when the downward pressing locking mechanism is in the unlocked state and the hook platform 44 on the rotating shaft 41 in the machine head locking mechanism does not hook into the hook groove 32, can the motor start button 3 be pressed; (2) When the motor start button 3 is pressed, the rotating shaft 41 cannot rotate forward, making the locking pin 42 in the machine head locking mechanism unable to extend to the working position, so that the machine head locking mechanism cannot lock the machine head at the saw blade replacement position.

[0026] In this embodiment, the driving member 4 is a handle. The lower end of the handle 4 is fixed to the outer end of the rotating shaft 41. Driving the handle 4 to swing forward can make the rotating shaft 41 rotate forward, and driving the handle 4 to swing backward can make the rotating shaft 41 rotate backward. On the housing of the machine head 1, there are also a front limiting convex edge 11 that can be abutted by the handle 4 swinging forward to limit the forward movement of the handle 4 and a rear limiting convex edge 12 that can be abutted by the handle 4 swinging backward to limit the backward movement of the handle 4.

[0027] A clamping platform 45 is provided at the outer end of the rotating shaft 41, and a clamping groove 46 is provided on the inner side of the lower end of the handle 4. The lower end of the handle 4 and the rotating shaft 41 are locked and fixed by screws. When fixed, the clamping platform 45 is snapped into the clamping groove 46, so that the handle 4 can drive the rotating shaft 41 to rotate through the matching clamping platform 45 and clamping groove 46.

[0028] As Figure 8 , Figure 9 shown, two elastic piece holes 7 arranged front and rear are provided on the surface of the housing of the machine head 1 opposite to the inner side wall of the handle 4. An elastic piece 71 with one end fixed to the housing of the machine head 1 and the other end unfixed is provided in each of the two elastic piece holes 7. A positioning boss protruding outward from the surface of the housing of the machine head 1 is provided on the outer surface of the unfixed end of each of the two elastic pieces 71. The two positioning bosses are a front positioning boss 61 and a rear positioning boss 62 respectively. A front positioning hole 51 and a rear positioning hole 52 are provided on the inner side wall of the handle 4. When the handle 4 swings back and forth, its inner side wall can squeeze the two positioning bosses respectively. When the positioning boss is squeezed, the elastic piece 71 where it is located will elastically deform inward, so that the two positioning bosses can move inward to abut against the inner side wall of the handle 4; when the handle 4 swings forward to abut against the front limit convex edge 11, the front positioning boss 61 can just be inserted into the front positioning hole 51 to perform front positioning on the handle 4; when the handle 4 swings backward to abut against the rear limit convex edge 12, the rear positioning boss 62 can just be inserted into the rear positioning hole 52 to perform rear positioning on the handle 4. Positioning the handle 4 is to prevent the handle 4 from swinging when it is not driven.

[0029] A U-shaped frame 47 straddling the housing of the machine head 1 is provided above the handle 4, and one side of the U-shaped frame 47 is fixed to the upper end of the handle 4. The U-shaped frame 47 is provided on the one hand to drive the handle 4 to swing more conveniently, and on the other hand to guide the forward and backward swing of the handle 4.

Claims

1. A safety interlock device for a power saw, Comprising: An installation frame mounted on a bottom plate, a machine head hinged to the installation frame, a downward pressing and locking mechanism arranged on the machine head, and a motor start button reset by a button spring. It is characterized in that: it further includes: a machine head locking mechanism, when the machine head is pressed down and swings downward to the position for replacing the saw blade, the machine head locking mechanism can lock the machine head so as to replace the saw blade; the structure of the downward pressing and locking mechanism is: a swing rod running back and forth, a downward pressing piece running left and right, and an unlocking block are arranged on the machine head shell. The middle parts of the swing rod and the downward pressing piece are respectively hinged to the machine head shell. The inner end of the downward pressing piece is lifted upward under the action of a piece torsion spring arranged in the machine head, so that the outer end of the downward pressing piece is pressed downward to a position where it can abut against a blocking block on the installation frame to prevent the machine head from swinging downward. At this time, the downward pressing and locking mechanism is in a locked state. The front end of the swing rod is located above the inner end of the downward pressing piece, and the rear end of the swing rod is fixed to the unlocking block. By driving the unlocking block to move upward, the front end of the swing rod can swing downward to press the inner end of the downward pressing piece, so that the outer end of the downward pressing piece can tilt upward to a position where it does not prevent the machine head from swinging downward. At this time, the downward pressing and locking mechanism is in an unlocked state. A reset spring is arranged above the rear end of the swing rod between the swing rod and the machine head shell, which can press the rear end of the swing rod downward to reset the unlocking block downward; the structure of the machine head locking mechanism is: a lock piece located on the side of the machine head is arranged on the installation frame. The rear end of the lock piece is hinged to the installation frame, so that the lock piece can swing up and down. An upward-opening lock groove is arranged at the front end of the lock piece. The lock piece swings upward under the action of a lock piece torsion spring arranged on the installation frame until its front end abuts against a limit bar on the installation frame. A rotatable shaft running left and right, a lock pin reset by a lock pin spring running left and right, and a driving part are arranged on the machine head shell. The inner end of the lock pin is arranged opposite to the inner end of the shaft. The outer end of the lock pin faces the side where the lock piece is located. A slope-shaped convex platform for pressing the lock pin is arranged at the inner end of the shaft. The outer end of the shaft is fixed to the driving part, so that the shaft can be driven to rotate through the driving part. And after the shaft is driven to rotate forward by the driving part, the slope-shaped convex platform can gradually press the lock pin outward through the slope surface, so that the outer end of the lock pin can extend out to the working position. The outer end of the lock pin in the working position can press the lock piece when the machine head swings downward, so that the lock piece can swing downward, so that the outer end of the lock pin can swing downward along the upper side of the lock piece. When the machine head swings downward to the position for replacing the saw blade, the outer end of the lock pin just moves above the lock groove. At this time, the lock piece will rotate upward and reset under the action of the lock piece torsion spring, so that the outer end of the lock pin is caught in the lock groove, so that the lock piece can lock the machine head. At this time, the machine head locking mechanism is in a locked state. When unlocking is required, after the shaft is driven to rotate reversely by the driving part, the slope-shaped convex platform will gradually release the pressing on the lock pin, so that the lock pin can retract under the action of the lock pin spring and disengage from the lock piece, so that the machine head locking mechanism can be in an unlocked state;A connecting rod that runs back and forth and can slide back and forth is also provided on the nose housing. Both the connecting rod and the rotating shaft are located below the swing rod, and the rotating shaft is located in front of the connecting rod. The connecting rod is fixed to the motor start button, so that the connecting rod can move backward as the motor start button is pressed. A blocking boss is provided on the side wall at the rear of the swing rod. When the pressing and locking mechanism is in the locked state, the blocking boss is located behind the connecting rod and can block the backward movement of the connecting rod, making it impossible for the connecting rod to move backward and preventing the motor start button from being pressed. When the pressing and locking mechanism is in the unlocked state, the blocking boss will swing upward with the rear end of the swing rod and will not block behind the connecting rod, enabling the motor start button to be pressed to start the motor. A hook groove with an open bottom is provided at the front end of the connecting rod, and a hook platform is provided on the rotating shaft. When the motor start button is not pressed, the hook platform can rotate upward and hook into the hook groove as the rotating shaft rotates forward, so as to abut against the front side wall of the hook groove, making it impossible for the connecting rod to move backward and preventing the motor start button from being pressed. After the motor start button is pressed, the bottom wall at the front end of the connecting rod will move backward to a position that blocks the forward rotation of the hook platform, making it impossible for the hook platform to rotate forward and preventing the rotating shaft from rotating forward, so that the locking pin cannot extend to the working position.

2. The safety interlock device for a power saw according to claim 1, Characterized in that: The driving member is a handle, the lower end of the handle is fixed to the outer end of the rotating shaft. After the handle is driven to swing forward, the rotating shaft can rotate forward, and after the handle is driven to swing backward, the rotating shaft can rotate backward. On the head housing, there are also provided a front limit convex edge for the forward-swinging handle to abut against for front limit of the handle and a rear limit convex edge for the backward-swinging handle to abut against for rear limit of the handle.

3. The safety interlock device for a power saw according to claim 2, Characterized in that: A clamping platform is arranged on the outer end of the rotating shaft, a clamping groove is arranged on the inner side of the lower end of the handle, and the lower end of the handle and the rotating shaft are locked and fixed by screws. When fixed, the clamping platform is clamped into the clamping groove, so that the handle can drive the rotating shaft to rotate through the matching clamping platform and clamping groove.

4. The safety interlock device for a power saw according to claim 2 or 3, Characterized in that: Two elastically deformed holes arranged front and rear are provided on the surface of the head housing opposite to the inner side wall of the handle. In each of the two elastically deformed holes, there is an elastic piece with one end fixed to the head housing and the other end unfixed. On the outer surface of the unfixed end of each of the two elastic pieces, there is a positioning convex platform protruding outward from the surface of the head housing. The two positioning convex platforms are respectively a front positioning convex platform and a rear positioning convex platform. A front positioning hole and a rear positioning hole are provided on the inner side wall of the handle. When the handle swings forward and backward, its inner side wall can respectively squeeze the two positioning convex platforms. When the positioning convex platform is squeezed, the elastic piece where it is located will elastically deform inward, so that the two positioning convex platforms can move inward and abut against the inner side wall of the handle; when the handle swings forward to abut against the front limit convex edge, the front positioning convex platform can just be inserted into the front positioning hole to perform front positioning on the handle; when the handle swings backward to abut against the rear limit convex edge, the rear positioning convex platform can just be inserted into the rear positioning hole to perform rear positioning on the handle.

5. The safety interlock device for a power saw according to claim 2 or 3, Characterized in that: A U-shaped frame straddling the head housing is arranged above the handle, and one side of the U-shaped frame is fixed to the upper end of the handle.

6. The safety interlock device for a power saw according to claim 1 or 2 or 3, Characterized in that: The hook groove is an arc-shaped hook groove, and the hook platform is an arc-shaped hook platform.

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