A camshaft driven straightening roll safety locking mechanism

Abstract

The invention discloses a camshaft driven straightening roll safety locking mechanism. The locking mechanism comprises: a chuck for mounting the locking mechanism on a rack; the chuck has a hollow shaft hole; a camshaft is slidably arranged in the shaft hole; a hydraulic cylinder is arranged at the tail of the camshaft; a claw head is arranged at the head of the camshaft; two or more than two 90 0 rotary guide grooves are arranged on the outer surface of the middle part of the camshaft; a positioning ball corresponding to each of the rotary guide grooves is arranged on the chuck; when the hydraulic cylinder moves forward, the camshaft moves forward and rotates 90 0 degrees under the cooperation of the positioning ball 90 0 rotary guide grooves, and the claw head is in the working position; when the hydraulic cylinder moves backward, the camshaft moves backward and rotates 90 0 degrees under the cooperation of the positioning ball 90 0 rotary guide grooves, and the claw head is out of the working position. The invention has the advantages of simple structure, convenient installation and reliable work.

Description

Technical Field

[0001] The present invention relates to a combined frame straightening machine, which adopts an automatic roller changing vehicle process and a camshaft-driven straightening roller safety locking mechanism during the process of transferring the straightening machine on the operating side frame to the roller shaft of the automatic roller changing vehicle. Background Art

[0002] Under the process conditions of group roll changing by automatic roll changing vehicle, a transverse track is arranged parallel to the straightening center line at a certain distance from the straightening machine for the movement of the automatic roll changing vehicle; the automatic roll changing vehicle is configured on the transverse track.

[0003] During straightening operations, the automatic roll changing vehicles stay at their respective waiting positions.

[0004] The main process of the roll changing operation is as follows: After unlocking the straightening roll system and the operating-side frame fastening conditions, the operating-side frame, driven by a hydraulic cylinder, moves with the straightening rolls along the longitudinal track along the straightening roll axis; upon reaching the roll changing position, the straightening rolls are radially removable. The unloaded automatic roll changing vehicle enters the frame roll changing area and stops at the roll changing position on the transverse track. The straightening roll carrying process moves the old straightening rolls from the operating-side frame to the automatic roll changing vehicle. The automatic roll changing vehicle carrying the old straightening rolls then moves out of the combined straightening machine roll changing area. The automatic roll changing vehicle carrying a set of new straightening rolls enters the frame roll changing area and stops at the roll changing position on the transverse track. The straightening roll carrying process inserts the new straightening rolls onto the roller shafts of the operating-side frame bearing seat. The unloaded automatic roll changing vehicle then exits the combined stand roll changing area.

[0005] In the above-mentioned roll changing process, no matter operating the side frame or the automatic roll changing vehicle, the functional structure for carrying the straightening roll is a cantilevered roll shaft; the way to carry the straightening roll is in the form of a short half-shaft inserted into the center hole of the straightening roll.

[0006] Because the straightening rollers require easy loading and unloading of the roller shafts when the automatic roller changing vehicle and the operating side frame are performing the straightening roller carrier exchange procedure, the outer diameters of the straightening roller bearing seats on the upper and lower operating side frames and the roller shafts used to suspend the straightening rollers in the automatic roller changing vehicle are slightly smaller than the inner diameters of the straightening rollers, forming a clearance fit; and the fit length is less than 1 / 2 of the straightening roller width. Therefore, the straightening rollers are prone to uncontrolled axial displacement during the carrier exchange process, and there is a risk of slipping off the cantilevered roller shaft. At the same time, due to the presence of a certain range of dimensional deviations in the axis centerline position, parallelism, coaxiality, and other dimensional deviations when the roller shafts on the automatic roller changing vehicle and the roller shafts in the operating side frame are aligned, this can cause detachment and obstruction during the exchange process. Summary of the Invention

[0007] In response to the above problems, the present invention provides a camshaft-driven straightening roller safety locking mechanism, which locks and fixes the relative position of the straightening roller and the operating side frame or the automatic roll changing vehicle to prevent uncontrolled slippage when the automatic roll changing vehicle and the operating side frame perform the straightening roller exchange procedure.

[0008] To achieve the above-mentioned object, the present invention provides a camshaft-driven straightening roller safety locking mechanism, wherein the locking mechanism comprises:

[0009] a chuck for mounting the locking mechanism on the frame;

[0010] The chuck has a hollow shaft hole;

[0011] A camshaft is slidably arranged in the shaft hole;

[0012] A hydraulic cylinder is provided at the tail end of the camshaft;

[0013] A claw head is provided on the camshaft head;

[0014] The outer surface of the middle part of the camshaft is provided with two or more 90 0 Rotational guide groove;

[0015] A positioning ball is provided on the chuck corresponding to each of the rotation guide grooves;

[0016] When the hydraulic cylinder moves forward, the camshaft is positioned at the position of the ball 90 0 Move forward and rotate 90 degrees with the cooperation of the rotating guide groove 0 , so that the claw head is in the working position; when the hydraulic cylinder moves backward, the camshaft is positioned at the position of the ball 90 0 The rotating guide groove moves backward and rotates 90 degrees. 0 , so that the claw head is out of the working position.

[0017] Furthermore, a claw position detection device is included, wherein the claw position detection device includes: a horizontal positioning protrusion and a vertical positioning protrusion are provided on the outer circumference of the tail of the camshaft, and a horizontal sensor and a vertical sensor are provided on the upper edge of the frame;

[0018] When the camshaft rotates 90 0 When the claw head is in the working position, the horizontal positioning convex block is close to the horizontal sensor and the horizontal sensor outputs a signal; when the camshaft rotates 90 degrees in the opposite direction, 0 When the claw head is disengaged from the working position, the vertical positioning protrusion comes close to the vertical sensor and the horizontal sensor outputs a signal.

[0019] Furthermore, a hollow roller is provided on the frame below the locking mechanism, and a sheathing detection device is provided on the side wall of the roller.

[0020] Furthermore, a through hole is provided on the side wall of the roller shaft, and the insertion detection device comprises a contact guide sleeve installed in the through hole, a contact rod is slidably provided in the contact guide sleeve, and the head of the contact rod is exposed outside the through hole for sensing the insertion of the straightening roller;

[0021] The contact rod is a stepped shaft-like part; the upper end is provided with a threaded structure and cooperates with a nut to fix the induction bracket; the middle section is provided with a spring; the lower portion of the middle section is provided with an enlarged cylindrical structure to limit the position in the contact guide seat (457); the bottom is spherical and is used to contact the cylindrical surface at the end of the straightening inner cavity to sense the straightening roller insertion position signal;

[0022] The free end of the sensing bracket is equipped with a sensing bolt, which can be adjusted relative to the sensing bracket. A switch bracket is installed in the hollow part of the roller shaft corresponding to the sensing bolt, and the switch bracket is equipped with a micro switch. The three main functional components are the claw position and insertion detection mechanism.

[0023] The camshaft-driven straightening roller safety locking mechanism of the present invention has the advantages of simple structure, convenient installation, reliable operation, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the camshaft-driven straightening roller safety locking mechanism.

[0025] Figure 2 for Figure 1 AA section view.

[0026] Figure 3 for Figure 1 BB cross-sectional view

[0027] Figure 4 for Figure 1 CC cross-sectional view

[0028] Figure 5 Schematic diagram of the camshaft assembly.

[0029] Figure 6 A partial enlarged diagram of the chuck

[0030] Figure 7 Position diagram of the claw head during camshaft change

[0031] Figure 8 Schematic diagram of the structure before the straightening roller is put into place.

[0032] Figure 9 for Figure 8 A partial enlarged schematic diagram.

[0033] Figure 10 Schematic diagram of the structure after the straightening roller is put into place.

[0034] Figure 11 for Figure 10 A partial enlarged schematic diagram.

[0035] Figure 12 Schematic diagram of horizontal posture detection of the pulling claw.

[0036] Figure 13 Schematic diagram of vertical posture detection of the pulling claw.

[0037] Figure 14 It is a schematic diagram of the structure of the insertion detection device. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings.

[0039] The camshaft-driven straightening roller safety locking mechanism is set on the upper part of the upper and lower straightening roller bearing seat structures on the operating side frame and above the roller shaft of the automatic roll changing vehicle. It is used to lock the straightening roller to ensure that the immediate status of the carrying body meets the set requirements when the straightening roller carrying and exchange procedure is executed.

[0040] The camshaft-driven straightening roller safety locking mechanism mainly consists of a claw head (471), a screw (472), a camshaft (473), a chuck (474), a chuck cover (475), a screw (476), a ball (477), a guide rod (478), a spring (479), a pressure block (481), a screw (482), a horizontal sensing block (483), a vertical sensing block (484), a screw (485), a hydraulic cylinder (486), a proximity switch (487), a base plate (488), a copper washer (489), etc., and is divided into three main functional component units: a camshaft assembly, a chuck assembly, and a claw posture and insertion detection mechanism.

[0041] As shown in the figure, the composition, relative position and assembly relationship of the camshaft-driven straightening roller safety locking mechanism are mainly composed of a claw head (471), a screw (472), a camshaft (473), a horizontal sensing block (483), a vertical sensing block (484), a screw (485), and a piston rod of a hydraulic cylinder (486), which constitute a camshaft assembly (470) for performing the locking function of the straightening roller.

[0042] The claw head (471) and the cam shaft (473) are connected by an assembled structure. The claw head (471) is provided with a countersunk hole structure to cooperate with the cam shaft (473) and is fastened to the cam shaft (473) by screws (472).

[0043] The cam shaft (473) is used to make the claw head (471) move 90 degrees.0 The camshaft (473) has a flat head structure for preventing rotation, which is used to fix the circumferential position between the claw head (471) and the camshaft (473). The middle section of the camshaft (473) is cylindrical, and the cylindrical surface is engraved with a 120 0 The three cylindrical spiral lines and the straight line compound curved groove are distributed; the curved section is used for the claw head (471) 90 0 Rotation, straight line section for the claw head (471) to complete 90 0 The linear displacement after rotation; the cross-sectional shape of the curved groove only allows half of the ball body to slide therein. The tail of the camshaft (473) has a stop flat head structure for determining the orientation of the horizontal sensing block (483), and the center screw hole is used to connect with the hydraulic cylinder (486).

[0044] The horizontal sensing block (483) is used to cooperate with the proximity switch (487) to sense that the pull claw head fixed at the front end of the camshaft (473) is in a vertical position; the vertical sensing block (484) is used to cooperate with the proximity switch (487) to sense that the pull claw head fixed at the front end of the camshaft (473) is in a horizontal position. The horizontal sensing block (483) is assembled on the anti-rotation flat head structure at the tail end of the camshaft (473), and the vertical sensing block (484) is assembled on the anti-rotation flat head structure of the piston rod head of the hydraulic cylinder (486). When the threaded section of the piston rod head is screwed into the central screw hole at the tail end of the camshaft (473), the two are connected and fastened with screws (485).

[0045] Chuck assembly: chuck (474), chuck cover (475), screw (476), ball (477), guide rod (478), spring (479), pressure block (481), screw (482) etc. constitute chuck assembly (480). Chuck assembly (480) is fixed on the operating side frame bearing seat or automatic roller changing vehicle; used to control the camshaft to move 90 degrees. 0 A compound motion of rotation and linear displacement.

[0046] The front and rear outer contours of the chuck (474) are cylindrical, and the middle part is rectangular; the four corners of the rectangle are provided with bolt holes for fixing, and the middle part is provided with a chuck cover (475) for use, 120 0 The front and rear ends of the chuck (474) are inlaid with copper tiles (489); used to center the camshaft (473). The front end of the chuck (474) and the chuck cover (475) are provided with a 120 0 The hole structure has a distributed hole structure. The hole structure near the center section is the working channel for the ball (477); the hole structure near the outer circle section is a countersunk hole structure, allowing the guide rod (478) and spring (479) to make micro movements therein. The outer contour of the rear end cylinder of the chuck (474) serves as the mating surface for assembly with the operating side frame bearing seat or the relevant parts of the automatic roller changing vehicle.

[0047] The chuck cover (475) is a disc-shaped structure; the inner circle matches the front cylindrical surface of the chuck (474), and the end surface is fixed on the rectangular vertical surface of the chuck (474). The chuck cover (475) is provided with three 120 corresponding to the chuck (474) 0 The distributed hole structure accommodates the guide rod (478), the spring (479), the pressure block (481), and the screw (482).

[0048] Working principle of the camshaft-driven straightening roller safety locking mechanism

[0049] 1) Requirements for the claw position during the straightening roller suspension exchange process

[0050] While achieving the claw safety locking function of the straightening roller, it is required that the straightening roller does not interfere with the cantilever roller shaft during insertion. Therefore, the claw head in the claw safety locking mechanism should have two working positions: vertical and horizontal. When the claw head is in the vertical position, the straightening roller can be installed on the roller shaft. After the straightening roller is installed on the roller shaft, the claw rotates to the horizontal position, and the claw head embeds in the groove of the straightening roller, preventing the straightening roller from moving toward the cantilever end of the roller shaft, thereby achieving a safe locking effect.

[0051] 2) Working principle of the camshaft driven straightening roller safety locking mechanism Since the chuck (474) is fixed at any time during the working process, the three straightening rollers are 120 degrees apart. 0 The balls (477), guide rods (478), springs (479), pressure blocks (481), and screws (482) contained in the distributed hole structure are then relatively fixed; at the same time, since the curved groove of the camshaft (473) only allows half of the ball body to slide therein, the other half of the ball body moves slightly in the hole of the chuck (474).

[0052] Before the straightening roller is inserted into the cantilever roller shaft, the claw head at the front of the cam shaft (473) is in a rear vertical position; the cam shaft assembly (470) is extended under the drive of the hydraulic cylinder; due to the limiting effect of the ball (477) in the chuck assembly (480) and the cylindrical spiral groove of the cam shaft (473), and the centering effect of the copper tile (489) embedded in the chuck (474) on the cam shaft (473), the cam shaft assembly (470) moves forward 90 degrees. 0 The composite motion of rotation and linear displacement; the claw head at the front of the cam shaft (473) changes from a vertical state before moving forward to a horizontal position after moving forward for a certain distance.

[0053] When the front claw of the camshaft (473) is in a horizontal position, the straightening roller can be inserted into the cantilever roller shaft without any external interference between the two. When the straightening roller is basically inserted into the cantilever roller shaft, the hydraulic cylinder drives the camshaft assembly (470) to retract. Under the combined action of the cylindrical spiral groove of the camshaft (473) and the ball (477), the camshaft (473) starts to reverse and retreat simultaneously, and the camshaft (473) drives the pull head (471) to rotate 90 degrees. 0 And retreat. When the lagua head (471) turns 90 0 At the end of the retraction process, the head of the pull-up head (471) has been inserted into the locking groove structure of the straightening roller; the vertical working surface of the pull-up head (471) is slightly away from the wall surface of the locking groove structure of the straightening roller. The hydraulic cylinder piston rod continues to retract, and the vertical working surface of the pull-up head (471) contacts the wall surface of the locking groove structure of the straightening roller, pulling the conical surface of the cantilever roller shaft at the end of the straightening roller to match the conical surface, thereby achieving the locking function. The locking state of the straightening roller is released and the reverse process is implemented.

[0054] Since the front claw of the camshaft (473) is in a horizontal position, the straightening roller can be inserted into the cantilever roller shaft without generating external interference between the two, and a certain gap can be reserved in the design. Therefore, the working state of the straightening roller is not affected when used on the straightening machine.

[0055] Claw position and insertion detection mechanism

[0056] 1) The function and role of the claw position and insertion detection mechanism

[0057] The claw position and insertion detection mechanism includes a claw position detection switch assembly and a straightening roller insertion detection assembly. The claw position detection device detects both the vertical and horizontal positions of the claw head. The straightening roller insertion detection mechanism measures the horizontal depth of the straightening roller inserted into the cantilevered roller shaft to prevent false positives of empty rollers.

[0058] Due to the dimensional limitations of the straightening roller groove axis, when the straightening roller is not inserted into the cantilever roller shaft, the claw position cannot be effectively rotated to the horizontal position, the claw groove head interferes with the straightening roller, and other factors cause the claw to fail to rotate to the horizontal position, thereby failing to eliminate the risk of the straightening roller slipping off the cantilever roller shaft. Therefore, a claw position detection device and a straightening roller insertion detection mechanism are set to ensure and verify the effectiveness of safety measures. Since the straightening roller is transferred from the automatic roll changing vehicle to the operating frame by forced movement of the operating frame, and the automatic roll changing vehicle needs to install the straightening roller on the cantilever roller shaft of the automatic roll changing vehicle in an open space and with manual assistance or individually, only a claw position detection device is set on the bearing seat on the operating frame, and a claw position detection device and a straightening roller insertion detection mechanism are set on the automatic roll changing vehicle.

[0059] 2) Pull claw position detection switch assembly

[0060] A claw position proximity detection switch assembly consisting of two proximity switches (487) and a base plate (488) is convenient for installation and adjustment.

[0061] The claw position detection switch assembly is installed above the camshaft assembly (470); when the camshaft assembly (470) is retracted into position along with the hydraulic cylinder piston rod, the claw head is in a vertical position, the protruding portion of the vertical sensing block (484) is sensed by the proximity switch (487b), and a vertical position signal of the claw head is detected; when the camshaft assembly (470) is extended into position along with the hydraulic cylinder piston rod, the claw head is in a horizontal position, the horizontal sensing block (483) is sensed by the proximity switch (487b), and a horizontal position signal of the claw head is detected.

[0062] 3) Insert the testing mechanism

[0063] The straightening roller insertion detection mechanism is assembled in the hollow structure of the cantilever roller shaft 501 of the automatic roller changing vehicle; through the influence of the straightening roller insertion position on the change of the contact position of the contact rod in the insertion detection mechanism, the signal is extracted to sense whether the straightening roller is in place during the roller shaft installation process.

[0064] The straightening roller insertion detection mechanism mainly consists of a contact rod (454), a spring (455), a contact guide sleeve (456), a contact guide seat (457), a nut (458), an induction bracket (459), an induction bolt (461), a micro switch (462), a switch bracket (463), an induction mechanism fixing seat (464), a fixing pin (465) and an auxiliary installation handle (466).

[0065] The contact rod (454) is used to sense the insertion of the straightening roller. The contact rod (454) is a stepped shaft-like part; the upper end has a threaded structure that cooperates with a nut to fix the sensing bracket (459); the middle section is used to carry a spring (455); the lower portion of the middle section has an enlarged cylindrical structure for limiting the position in the contact guide seat (457); the bottom is a spherical structure for contacting the cylindrical surface at the end of the straightening inner cavity to sense the straightening roller insertion position signal.

[0066] The inner cavity of the contact guide sleeve (456) is used to assemble parts such as the contact rod (454), the spring (455), and the nut (458). The upper surface of the contact guide sleeve (456) has a threaded structure, the middle portion is cylindrical, and the lower portion has a jaw clamping structure. The contact guide sleeve (456), the spring (455), and the nut (458) constitute a contact guide sleeve assembly.

[0067] The contact guide seat (457) is used to carry the contact guide sleeve assembly. The outer contour of the lower portion of the contact guide seat (457) matches the inner diameter of the cantilever roller shaft, and screw countersunk structures are provided on both sides for positioning and fixing the contact guide seat in the inner cavity of the roller shaft; a screw hole is provided on the front elevation for installing an auxiliary handle (466).

[0068] The induction bracket (459) is a "Z"-shaped sheet metal component, one end of which is connected to the top of the contact rod (454), and the other end is used to carry the induction bolt (461). The induction bolt (461) can be adjusted in position on the induction bracket (459).

[0069] The contact rod (454) is inserted into the spring (455) and then installed in the contact guide seat (457), and then locked with a nut (458); the working stroke of the spring (455) is slightly greater than the chord height of the ball head at the lower end of the contact rod, ensuring that the contact rod (454) can move a certain vertical stroke in the contact guide seat (457). The nut (458) can also be adjusted to fine-tune the stroke of the contact rod (454) in the contact guide seat (457).

[0070] The micro switch (462) is assembled on the switch bracket (463); the switch bracket (463) is fixed on the induction mechanism fixing seat (464).

[0071] The sensing mechanism fixing seat (464) is used to carry a micro switch (462), a switch bracket (463), etc. The outer contour of the lower portion of the sensing mechanism fixing seat (464) matches the inner diameter of the cantilever roller shaft, and screw countersunk structures for positioning and fixing it in the inner cavity of the roller shaft are provided on both sides; a screw hole structure for assembling a fixing pin (465) is provided in the middle; and a screw hole is provided on the rear end vertical surface for installing an auxiliary handle (466).

[0072] Since the assembly position of the straightening roller into the detection mechanism is within the limited space of the cantilever roller shaft cavity, the auxiliary handle (466) is used during assembly and is screwed into the contact guide seat (457) and the sensing mechanism fixing seat (464) respectively. After the assembly is completed, the auxiliary handle (466) is screwed out.

[0073] The working principle of the insertion detection mechanism is as follows:

[0074] When the detection mechanism is inserted into the inner cavity of the roller shaft, only the ball head of the contact rod (454) is exposed on the cylindrical surface of the inner cavity of the roller shaft; when the straightening roller is not inserted into the cantilever roller shaft or is not in place, the ball head of the contact rod inserted into the detection mechanism remains exposed; the sensing bracket (459) and the sensing bolt (461) linked to the contact rod remain in the same position, and a certain gap is left between the top surface of the sensing bolt (461) and the micro switch (462).

[0075] When the straightening roller is installed in place, the ball head of the contact rod (454) is constrained by the cylindrical surface of the roller shaft. During the axial movement of the straightening roller, the contact rod (454) compresses the spring (455) in the contact guide sleeve (456), driving the sensing bracket (459) to move upward; when the sensing bracket (459) moves up to the position, the head surface of the sensing bolt (461) contacts the contact of the micro switch (462), causing it to retract, thereby triggering the relevant mechanism inside the micro switch (462) to send a signal, indicating that the straightening roller has reached the preset position after axial movement on the roller shaft.

[0076] The signal from the insertion detection mechanism indicating that the straightening roller has reached the preset position is used to uniquely indicate that the pull claw has been inserted into the cantilever roller shaft and has reached the preset position. This prevents any misjudgment of the pull claw being locked.

Claims

1. A camshaft driven straightening roller safety locking mechanism, characterized in that: The locking mechanism comprises: a chuck for mounting the locking mechanism on the frame; The chuck has a hollow shaft hole; A camshaft is slidably arranged in the shaft hole; A hydraulic cylinder is provided at the tail end of the camshaft; A claw head is provided on the camshaft head; The outer surface of the middle part of the camshaft is provided with two or more 90 0 Rotational guide groove; A positioning ball is provided on the chuck corresponding to each of the rotation guide grooves; When the hydraulic cylinder moves forward, the camshaft is positioned at the position of the ball 90 0 Move forward and rotate 90 degrees with the cooperation of the rotating guide groove 0 , so that the claw head is in the working position; when the hydraulic cylinder moves backward, the camshaft is positioned at the position of the ball 90 0 The rotating guide groove moves backward and rotates 90 degrees. 0 , so that the claw head is out of the working position; A hollow roller shaft is arranged on the frame below the locking mechanism, and a sheathing detection device is arranged on the inner side of the roller shaft.

2. The camshaft-driven straightening roller safety locking mechanism according to claim 1, characterized in that: It also includes a claw position detection device, which includes: a horizontal positioning protrusion and a vertical positioning protrusion are provided on the outer circumference of the tail of the camshaft, and a horizontal sensor and a vertical sensor are provided on the upper edge of the frame; When the camshaft rotates 90 0 When the claw head is in the working position, the horizontal positioning convex block is close to the horizontal sensor and the horizontal sensor outputs a signal; when the camshaft rotates 90 degrees in the opposite direction, 0 When the claw head is disengaged from the working position, the vertical positioning protrusion comes close to the vertical sensor and the horizontal sensor outputs a signal.

3. The camshaft-driven straightening roller safety locking mechanism according to claim 1, characterized in that: A through hole is provided on the side wall of the roller shaft, and the insertion detection device comprises a contact guide sleeve installed in the through hole, a contact rod is slidably provided in the contact guide sleeve, and the head of the contact rod is exposed outside the through hole for sensing the insertion of the straightening roller; The contact rod is a stepped shaft-like part; the upper end has a threaded structure that cooperates with a nut to fix the sensing bracket; the middle section is equipped with a spring; the lower part of the middle section has an enlarged cylindrical structure to limit the position within the contact guide seat; the bottom is spherical and is used to contact the cylindrical surface at the end of the straightening cavity to sense the straightening roller insertion position signal; The free end of the induction bracket is provided with an induction bolt, and the position of the induction bolt can be adjusted relative to the induction bracket; a switch bracket is provided in the hollow part of the roller shaft corresponding to the induction bolt, and a micro switch is provided on the switch bracket.

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