A depth-limiting stepped positioning device for in-hole concentric drilling based on a torque-limiting structure and a method thereof

Abstract

The present application relates to the technical field of hole drilling, in particular to a depth-limiting stepped positioning device for hole drilling based on a torque limiting structure and a method thereof, which comprises an external device sleeved on the outside of an electric hammer body, the electric hammer body is internally provided with an electric control torque limiting mechanism, the external device comprises a depth-limiting assembly for limiting the drilling depth, a positioning seat arranged at the end of the depth-limiting assembly, and a clamping assembly arranged in the positioning seat. The present application realizes preliminary radial positioning by the fit of the positioning block and the inner wall of the machined large hole, and realizes double concentric positioning by the extrusion of the extrusion block by the workpiece end face to trigger the clamping assembly to abut against the large hole wall, effectively eliminates the concentricity error caused by the machining deviation or edge collapse of the large hole, and ensures the coaxiality of the large and small holes.

Description

Technical Field

[0001] This invention relates to the field of concentric drilling technology, and more specifically, to a depth-determinable stepped positioning device and method for concentric drilling based on a torque limiting structure. Background Technology

[0002] In construction, decoration, and equipment installation, it is often necessary to drill coaxial smaller holes inside pre-formed large holes. For example, drilling anchor bolt holes inside large holes for embedded sleeves or drilling expansion bolt positioning holes inside large holes reserved for wiring in walls. Traditional construction methods rely on manual drilling with a handheld electric hammer. Due to the lack of a positioning reference, the drill bit is prone to deviation, resulting in misalignment between the large and small holes and assembly failure.

[0003] Patent application CN202322769772.9 discloses a silent electric drill, including a feeder assembly and a drill main unit. The drill main unit is mounted on the feeder assembly, and the drill main unit's spindle is connected to a drill bit via a spring collet. When the drill bit reaches a specified drilling depth, the drill main unit contacts the positioning slider to press the stop button, thereby stopping the movement of the lead screw drive pair. The drill can automatically control the drilling depth by drilling to the specified depth and then stopping.

[0004] However, the drilling aids on the market can only achieve a single depth limit function and cannot provide a concentric positioning reference inside the large hole, making them unsuitable for stepped drilling conditions with internal core drills. Secondly, when manually drilling with a handheld electric hammer, the drill bit is prone to shifting within the already machined large hole, and the large hole itself may have dimensional deviations or chipped edges during the initial machining. Relying solely on a fixed-size positioning structure cannot completely eliminate the impact of these defects, making it difficult to guarantee the coaxiality of the large and small holes.

[0005] In view of this, this application proposes a depth-determinable stepped positioning device and method for concentric drilling in holes based on a torque limiting structure. Summary of the Invention

[0006] The purpose of this invention is to provide a depth-determinable stepped positioning device and method for concentric drilling in holes based on a torque limiting structure. The device achieves initial radial positioning by the fit between the positioning block and the inner wall of the machined large hole. At the same time, the clamping component is triggered to press against the wall of the large hole outward by the pressure of the extrusion block being pressed by the end face of the workpiece, thereby achieving double concentric positioning and solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A depth-determinable stepped positioning device for concentric drilling in a hole based on a torque limiting structure includes an external connector sleeved on the outside of an electric hammer body. An electrically controlled torque limiting mechanism is provided inside the electric hammer body. The external connector includes a depth-determining component for limiting the drilling depth, a positioning seat disposed at the end of the depth-determining component, and a clamping component disposed inside the positioning seat. The end face of the positioning seat is provided with a positioning block whose outer diameter is adapted to the inner diameter of the machined large hole. Two extrusion blocks are also slidably embedded on the end face of the positioning seat, and the ends of the extrusion blocks are provided with inclined chamfers. The clamping assembly includes a telescopic frame slidably disposed inside the positioning seat, a slider connected to the telescopic frame, and a clamping frame disposed at the end of the slider. The telescopic frame is provided with an inclined block that is adapted to and slidably connected to the inclined chamfer. In the aforementioned equipment, when the positioning block is inserted into the machined large hole, the extrusion block is squeezed by the end face of the workpiece and shrinks into the positioning seat. The inclined chamfer of the extrusion block pushes the inclined block to drive the telescopic frame and the slider to move, so that the clamping frame extends outward to press against the wall of the large hole, thereby achieving concentric positioning between the positioning seat and the machined large hole.

[0008] In the technical solution of the present invention, the depth-fixing component includes a flat plate, a pair of guide rails fixedly connected to the outer wall of the flat plate by bolts, a slide table slidably disposed on the guide rails, a clamp fixedly connected to the slide table by bolts for gripping the electric hammer body, a slide rod fixedly connected to the outer wall of the flat plate by bolts, a first spring sleeved on the outside of the slide rod, a limiting frame slidably disposed on the slide table, and a pair of locking pins threadedly connected to the outer wall of the limiting frame. The bracket on the slide table is slidably sleeved on the outside of the slide rod, and the elastic force provided by the first spring pushes the slide table to move away from the positioning seat.

[0009] In the technical solution of the present invention, the depth-fixing component further includes indicator marks disposed on both sides of the limiting frame and two rulers fixedly connected to the outer wall of the plate by screws.

[0010] In the aforementioned equipment, the external connector moves synchronously with the electric hammer body through the sliding cooperation between the slide table and the guide rail. The limit frame slides on the slide table to set the drilling depth. After the locking pin locks, it abuts against the positioning seat when the electric hammer is fed to achieve mechanical hard limit, thereby achieving precise control of the drilling depth.

[0011] In the technical solution of the present invention, the positioning seat further includes a connecting plate fixedly connected to the end of the flat plate by bolts, a protective cover welded and fixed to the outer wall of the connecting plate, and an annular cover fixedly connected to the outer wall of the connecting plate by screws, wherein the positioning block is integrally formed at the end of the annular cover.

[0012] In the technical solution of the present invention, the center of the positioning seat is provided with a bushing through which the drill bit passes. The bushing is fixedly connected to the side of the protective cover near the electric hammer by screws, and the center of the bushing is provided with a round hole for the drill bit to pass through.

[0013] In the technical solution of the present invention, the protective cover has an integrally formed ring plate in the internal cavity, the ring plate has a through groove, the ring cover has a through groove for the extrusion block to slide, and the positioning seat also includes a discharge pipe for discharging dust generated by drilling, which is snapped and fixed between the outer cover body of the protective cover and the ring plate.

[0014] In the aforementioned equipment, preliminary radial positioning is achieved by the contact between the positioning block and the inner wall of the large hole, axial positioning is achieved by the contact between the end face of the annular cover and the surface of the workpiece, and the clamping assembly is triggered by the compression of the extrusion block by the end face of the workpiece. The three work together to achieve reliable positioning of the positioning seat and the machined large hole.

[0015] In the technical solution of the present invention, the clamping assembly further includes a pressure rod fixedly connected to the ends of a pair of sliders by bolts, a limiting rod slidably sleeved inside the pressure rod, and several second springs welded to the outer wall of the pressure rod.

[0016] In the technical solution of the present invention, the clamping frame is sleeved on the outside of the pressure rod, the limiting rod is fixedly connected to the clamping frame through the thread at its end, the end of the second spring is sleeved in the groove of the outer wall of the clamping frame, and the elastic force provided by the second spring pushes the clamping frame to move away from the pressure rod.

[0017] In the technical solution of the present invention, the telescopic frame is slidably fitted with a round rod, and a third spring is fitted on the outer side of the round rod. The two ends of the round rod are respectively snapped and fixed to the inside of the ring plate and the inner wall of the protective cover.

[0018] In the aforementioned equipment, the axial contraction motion of the extrusion block is converted into the radial extension motion of the clamping frame by the chamfer of the extrusion block and the inclined surface of the telescopic frame. This allows the clamping frame to automatically press against the hole wall inside the large hole, achieving double concentric positioning together with the positioning block, effectively eliminating concentricity errors caused by large hole machining deviations or edge chipping.

[0019] On the other hand, the present invention also provides a depth-determinable stepped positioning method for concentric drilling within a hole based on a torque limiting structure. Using the aforementioned depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure, the method includes the following steps: S1. Select a positioning block with a matching outer diameter according to the inner diameter of the machined large hole, put the external connector on the outside of the electric hammer body, and fix it to the electric hammer body by clamping it tightly, so that the slide moves synchronously with the electric hammer body. S2. Slide the limit frame along the slide table. Use the indicator marks on both sides of the limit frame and the scale on the guide rail to read and set the required drilling depth value. Then tighten the locking pin. The end of the locking pin abuts against the surface of the slide table to lock the limit frame on the slide table. S3. Align the positioning block at the end of the positioning seat with and insert it into the machined large hole. The outer wall of the positioning block fits against the inner wall of the large hole to achieve radial positioning of the positioning seat and the machined large hole. Continue to advance the positioning seat until the end face of the annular cover fits against the workpiece surface to achieve axial positioning. S4. During the process of advancing the positioning seat, the extrusion block is squeezed by the end face of the workpiece and shrinks into the positioning seat. The inclined chamfer at the end of the extrusion block pushes the inclined block on the telescopic frame, which drives the telescopic frame to move away from the extrusion block and compresses the third spring. The telescopic frame drives the slider to move synchronously through the round rod. The slider pushes the clamping frame to extend outward through the pressure rod until the clamping frame presses against the wall of the large hole and the pressure rod and the clamping frame form a rigid contact, realizing the double concentric positioning of the positioning seat and the machined large hole. S5. Start the electric hammer. The drill bit passes through the central hole of the bushing. The bushing guides the drill bit radially. Drilling is performed in the center of the large hole. The dust generated during drilling is discharged through the discharge pipe. S6. When the drill bit is fed to the preset drilling depth, the limit frame abuts against the connecting plate of the positioning seat, forcibly stopping the feed and completing the drilling. During the drilling process, when the cutting resistance of the drill bit exceeds the preset threshold of the electric torque limit mechanism inside the electric hammer, the electric torque limit mechanism automatically cuts off the feed. S7. Turn off the electric hammer, remove the drill bit, take the external connector out of the machined large hole, the clamping assembly is reset under the action of the third spring, and the extrusion block extends out of the end face of the positioning seat.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. The depth-determinable stepped positioning device and method for concentric drilling in holes based on torque limiting structure achieves preliminary radial positioning by the fit of the positioning block with the inner wall of the machined large hole. At the same time, the clamping component is triggered to press against the wall of the large hole by the extrusion block being squeezed by the end face of the workpiece, thereby achieving double concentric positioning. This effectively eliminates the concentricity error caused by the machining deviation or chipping of the large hole, and ensures the coaxiality of the large and small holes.

[0021] 2. The depth-determining stepped positioning device and method for concentric drilling in holes based on torque limiting structure accurately sets the drilling depth by sliding the limiting frame on the slide table in conjunction with the scale. After the locking pin locks, a mechanical hard limit is formed, and the drill bit is forcibly stopped when it reaches the preset depth, eliminating the error of depth by manual visual estimation, and is suitable for batch drilling construction.

[0022] 3. The depth-determinable stepped positioning device and method for concentric drilling in holes based on torque limiting structure, through the cooperation of the inclined chamfer of the extrusion block and the inclined surface of the telescopic frame, transforms the horizontal contraction motion of the extrusion block into the radial extension motion of the clamping frame, thereby realizing the automatic triggering of the clamping action during the insertion of the positioning seat into the large hole. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a side view of the overall structure of the present invention; Figure 3 This is one of the structural schematic diagrams of the external connector in this invention; Figure 4 This is the second schematic diagram of the external connector in this invention; Figure 5 This is a side view of the external connector in this invention. Figure 6 This is one of the structural schematic diagrams of the depth-fixing component in this invention; Figure 7 This is the second schematic diagram of the depth-fixing component in this invention; Figure 8 This is a cross-sectional schematic diagram of the positioning seat in this invention; Figure 9 This is a sectional side view of the positioning seat in this invention; Figure 10 This is a cross-sectional view of the positioning seat in this invention. Figure 11 This is a schematic diagram of the clamping component in the present invention; Figure 12 This is a partial cross-sectional schematic diagram of the clamping component in this invention; Explanation of reference numerals in the attached figures: 100. External connector; 110. Depth-fixing assembly; 111. Flat plate; 112. Guide rail; 113. Slide table; 114. Clamp; 115. Slide rod; 116. First spring; 117. Limiting frame; 118. Locking pin; 119. Scale; 120. Positioning seat; 121. Connecting plate; 122. Protective cover; 1220. Ring plate; 1221. Slide groove; 123. Annular cover; 1230. Through groove; 124. Positioning block; 125. Bushing; 126. Extrusion block; 127. Discharge pipe; 130. Clamping assembly; 131. Telescopic frame; 1310. Inclined block; 132. Slider; 133. Pressure rod; 134. Limiting rod; 135. Second spring; 136. Clamping frame; 137. Round rod; 138. Third spring. Detailed Implementation

[0024] The technical solutions of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] Please see Figures 1-7 As shown, this embodiment provides a technical solution: A depth-determinable stepped positioning device for concentric drilling in a hole based on a torque limiting structure includes an external connector 100 sleeved on the outside of the electric hammer body. An electrically controlled torque limiting mechanism is provided inside the electric hammer body. The external connector 100 includes a depth-determining component 110 for limiting the drilling depth, a positioning seat 120 disposed at the end of the depth-determining component 110, and a clamping component 130 disposed inside the positioning seat 120.

[0026] Furthermore, the electric hammer machine body is equipped with an electronically controlled torque limiting mechanism. The controller monitors the motor current in real time. Since the torque of the permanent magnet excited DC motor is roughly proportional to the motor current, the corresponding output torque can be limited by limiting the motor current. When the cutting resistance of the drill bit exceeds the preset threshold, the controller automatically reduces the motor output torque or cuts off the power transmission to prevent the excessive reaction torque generated when the drill bit is stuck from causing the machine body to rebound and injure people. The above is the existing technology and will not be elaborated here.

[0027] Furthermore, the depth-fixing assembly 110 includes a flat plate 111, a pair of guide rails 112 bolted to the outer wall of the flat plate 111, a slide table 113 slidably disposed on the guide rails 112, a clamp 114 bolted to the slide table 113 for gripping the hammer drill body, a slide rod 115 bolted to the outer wall of the flat plate 111, a first spring 116 sleeved on the outside of the slide rod 115, a limiting frame 117 slidably disposed on the slide table 113, and a pair of locking pins 118 threaded to the outer wall of the limiting frame 117. The bracket on the slide table 113 is slidably sleeved on the outside of the slide rod 115. The elastic force provided by the first spring 116 pushes the slide table 113 to move away from the positioning seat 120. The limiting frame 117 is locked on the slide table 113 by the locking pins 118. When the hammer drill feeds forward, the limiting frame 117 abuts against the positioning seat 120 to limit the maximum feed depth of the drill bit.

[0028] Furthermore, the depth setting component 110 also includes indicator marks on both sides of the limiting frame 117 and two scales 119 fixed to the outer wall of the plate 111 by screws. When the limiting frame 117 slides on the slide table 113, the drilling depth value is read and set by the indicator marks and scales 119. The locking pin 118 is a set screw structure. When tightened, the end of the locking pin 118 abuts against the surface of the slide table 113 to lock the limiting frame 117 on the slide table 113. When loosened, the locking is released, and the limiting frame 117 can slide freely on the slide table 113 to adjust the drilling depth.

[0029] Furthermore, the plate 111 serves as the mounting base for the depth-fixing component 110, and a square groove is provided inside for the slide table 113 to move along its outer wall support; the guide rail 112 is fixedly mounted on both sides of the outer wall of the plate 111, providing sliding guidance for the slide table 113; the slide table 113 can slide back and forth along the guide rail 112, serving to support the clamp 114 and the limiting frame 117 and move synchronously with the electric hammer body; the clamp 114 is used to hold and fix the slide table 113 to the electric hammer body, so that the slide table 113 moves synchronously with the electric hammer body; the limiting frame 117 is used to set the drilling depth; the locking pin 118 is used to lock the limiting frame 117 to the set position on the slide table 113; the indicator and scale 119 are used to read and set the drilling depth value.

[0030] In the above-mentioned equipment, the external connector 100 moves synchronously with the electric hammer body through the sliding cooperation between the slide table 113 and the guide rail 112. The limit frame 117 slides on the slide table 113 to set the drilling depth. After the locking pin 118 locks, it abuts against the positioning seat 120 when the electric hammer is fed to achieve mechanical hard limit, thereby realizing precise control of the drilling depth.

[0031] Please see Figures 8-10 As shown, in this embodiment, the positioning seat 120 includes a connecting plate 121 fixedly connected to the end of the flat plate 111 by bolts, a protective cover 122 welded and fixed to the outer wall of the connecting plate 121, and an annular cover 123 fixedly connected to the outer wall of the connecting plate 121 by screws. The end face of the positioning seat 120 is provided with a positioning block 124 whose outer diameter is adapted to the inner diameter of the machined large hole. The center of the positioning seat 120 is provided with a bushing 125 for the drill bit to pass through. Two extrusion blocks 126 are also slidably embedded on the end face of the positioning seat 120. The ends of the extrusion blocks 126 are provided with inclined chamfers.

[0032] Furthermore, the positioning block 124 is integrally formed at the end of the annular cover 123. The bushing 125 is fixedly connected to the protective cover 122 on the side near the electric hammer by screws. The bushing 125 has a circular hole in the center for the drill bit to pass through. The bushing 125 can be replaced according to different drill bit specifications.

[0033] Furthermore, the protective cover 122 has an integrally formed annular plate 1220 inside the cavity, and a sliding groove 1221 is provided through the annular plate 1220. A through groove 1230 is provided through the annular cover 123 for the extrusion block 126 to slide. The positioning seat 120 also includes a discharge pipe 127 that is snapped and fixed between the outer cover of the protective cover 122 and the annular plate 1220 for discharging the dust generated by drilling. The port of the discharge pipe 127 can be connected to an external vacuum cleaner.

[0034] Furthermore, the connecting plate 121 is used to fix the positioning seat 120 to the end of the depth-fixing component 110; the protective cover 122 is the outer shell of the positioning seat 120, used to accommodate the clamping component 130 and provide protection; the annular cover 123 is used to install the positioning block 124 and the pressing block 126, and its end face is used to fit against the workpiece surface after the positioning block 124 is fully inserted into the large hole to achieve axial positioning; the positioning block 124 is used to insert into the machined large hole and fit against the inner wall of the large hole to achieve radial positioning of the positioning seat 120.

[0035] Furthermore, the bushing 125 is used to radially guide the drill bit passing through it, ensuring the concentricity of the drill bit and the positioning seat 120; the extrusion block 126 is slidably embedded in the through groove 1230 of the annular cover 123 and its longitudinal section is T-shaped, with its end extending out of the end face of the annular cover 123, and is used to retract into the positioning seat 120 when squeezed by the end face of the workpiece, and trigger the action of the clamping assembly 130 by tilting and chamfering; the ring plate 1220 and the slide groove 1221 are used to provide sliding guidance for the telescopic frame 131 and the slider 132; the discharge pipe 127 is used to discharge the dust generated by drilling.

[0036] In the above-mentioned equipment, the initial radial positioning is achieved by the contact of the positioning block 124 with the inner wall of the large hole, the axial positioning is achieved by the contact of the end face of the annular cover 123 with the surface of the workpiece, and the clamping assembly 130 is triggered to move by the compression block 126 being squeezed and contracted by the end face of the workpiece. The three work together to achieve reliable positioning of the positioning seat 120 with the machined large hole.

[0037] Please see Figures 11-12 As shown, in this embodiment, the clamping assembly 130 includes a telescopic frame 131 slidably disposed inside the positioning seat 120, a slider 132 connected to the telescopic frame 131, a pressure rod 133 fixedly connected to the ends of a pair of sliders 132 by bolts, a limiting rod 134 slidably sleeved inside the pressure rod 133, a plurality of second springs 135 welded to the outer wall of the pressure rod 133, and a clamping frame 136 disposed at the ends of the sliders 132. The telescopic frame 131 is provided with an inclined block 1310 that is adapted to and slidably connected to the inclined chamfer.

[0038] Furthermore, when the positioning block 124 is inserted into the machined large hole, the extrusion block 126 is squeezed by the end face of the workpiece and shrinks into the positioning seat 120. The inclined chamfer of the extrusion block 126 pushes the inclined block 1310 to drive the telescopic frame 131 and the slider 132 to move, so that the clamping frame 136 extends outward to press against the wall of the large hole, thereby realizing the concentric positioning of the positioning seat 120 and the machined large hole.

[0039] Furthermore, the clamping frame 136 is sleeved on the outside of the pressure rod 133, the limiting rod 134 is fixedly connected to the clamping frame 136 through the thread at its end, and the end of the second spring 135 is sleeved in the groove on the outer wall of the clamping frame 136. The elastic force provided by the second spring 135 pushes the clamping frame 136 to move away from the pressure rod 133.

[0040] Furthermore, the telescopic frame 131 is slidably fitted with a round rod 137, and a third spring 138 is fitted on the outer side of the round rod 137. The two ends of the round rod 137 are respectively snapped and fixed to the inside of the ring plate 1220 and the inner wall of the protective cover 122.

[0041] Furthermore, the telescopic frame 131 is slidably disposed inside the positioning seat 120. Through the inclined chamfering of the inclined block 1310 and the pressing block 126, the contraction movement of the pressing block 126 is converted into the sliding of the telescopic frame 131. The slider 132 is connected to the telescopic frame 131 and is used to transmit the movement of the telescopic frame 131 to the pressure rod 133. The pressure rod 133 is used to push the clamping frame 136 to extend outward. The limiting rod 134 is used to limit the maximum extension distance of the clamping frame 136.

[0042] Furthermore, the second spring 135 is used to provide cushioning after the clamping frame 136 abuts against the hole wall and to ensure that the pressure rod 133 and the clamping frame 136 form a rigid contact; the clamping frame 136 is disposed at the end of the slider 132 and is used to extend outward to abut against the hole wall of the large hole; the round rod 137 and the third spring 138 are used to provide sliding guidance and reset elasticity for the telescopic frame 131.

[0043] In the aforementioned device, the axial contraction motion of the extrusion block 126 is converted into the radial extension motion of the clamping frame 136 by the inclined chamfer of the extrusion block 126 and the inclined surface of the inclined block 1310 of the telescopic frame 131. This allows the clamping frame 136 to automatically press against the hole wall inside the large hole, achieving double concentric positioning together with the positioning block 124, effectively eliminating concentricity errors caused by large hole processing deviations or edge chipping.

[0044] The present invention provides a depth-determinable stepped positioning method for concentric drilling within a hole based on a torque-limiting structure, using the aforementioned depth-determinable stepped positioning device for concentric drilling within a hole based on a torque-limiting structure, and includes the following steps: S1. Select a positioning block 124 with a matching outer diameter according to the inner diameter of the machined large hole, put the external connector 100 on the outside of the electric hammer body, and fix it to the electric hammer body by clamping 114, so that the slide table 113 moves synchronously with the electric hammer body and compresses the first spring 116. S2. Slide the limiting frame 117 along the slide table 113. The indicator marks on both sides of the limiting frame 117 cooperate with the scale 119 on the guide rail 112 to read and set the required drilling depth value. Then tighten the locking pin 118. The end of the locking pin 118 abuts against the surface of the slide table 113 to lock the limiting frame 117 on the slide table 113. S3. Align the positioning block 124 at the end of the positioning seat 120 and insert it into the machined large hole. The outer wall of the positioning block 124 fits against the inner wall of the large hole to achieve radial positioning of the positioning seat 120 and the machined large hole. Continue to advance the positioning seat 120 until the end face of the annular cover 123 fits against the workpiece surface to achieve axial positioning. S4. During the process of advancing the positioning seat 120, the extrusion block 126 is squeezed by the end face of the workpiece and shrinks into the positioning seat 120. The inclined chamfer at the end of the extrusion block 126 pushes the inclined block 1310 on the telescopic frame 131, causing the telescopic frame 131 to move away from the extrusion block 126 and compress the third spring 138. The telescopic frame 131 drives the slider 132 to move synchronously through the round rod 137. The slider 132 pushes the clamping frame 136 to extend outward through the pressure rod 133 until the clamping frame 136 presses against the wall of the large hole and the pressure rod 133 forms a rigid contact with the clamping frame 136, thereby realizing the double concentric positioning of the positioning seat 120 and the machined large hole. S5. Start the electric hammer. The drill bit passes through the central hole of the bushing 125. The bushing 125 guides the drill bit radially. Small hole drilling is performed in the center of the large hole. The dust generated during drilling is discharged through the discharge pipe 127. S6. When the drill bit is fed to the preset drilling depth, the limit frame 117 abuts against the connecting plate 121 of the positioning seat 120, forcibly stopping the feed and completing the drilling. During the drilling process, when the cutting resistance of the drill bit exceeds the preset threshold of the electric torque limit mechanism inside the electric hammer, the electric torque limit mechanism automatically cuts off the feed. S7. Turn off the electric hammer, remove the drill bit, take the external connector 100 out of the machined large hole, the slide table 113 is reset under the action of the first spring 116, the clamping assembly 130 is reset under the action of the third spring 138, and the pressing block 126 extends out of the end face of the positioning seat 120.

[0045] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the specification and its equivalents.

Claims

1. A depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure, comprising an external connector sleeved on the outside of an electric hammer body, wherein an electrically controlled torque limiting mechanism is provided inside the electric hammer body, characterized in that: The external connector includes a depth-limiting component for limiting the drilling depth, a positioning seat disposed at the end of the depth-limiting component, and a clamping component disposed inside the positioning seat. The end face of the positioning seat is provided with a positioning block whose outer diameter is adapted to the inner diameter of the machined large hole. Two extrusion blocks are also slidably embedded on the end face of the positioning seat, and the ends of the extrusion blocks are provided with inclined chamfers. The clamping assembly includes a telescopic frame slidably disposed inside the positioning seat, a slider connected to the telescopic frame, and a clamping frame disposed at the end of the slider. The telescopic frame is provided with an inclined block that is adapted to and slidably connected to the inclined chamfer. When the positioning block is inserted into the machined large hole, the extrusion block is squeezed by the end face of the workpiece and shrinks into the positioning seat. The inclined chamfer of the extrusion block pushes the inclined block to drive the telescopic frame and the slider to move, so that the clamping frame extends outward to press against the wall of the large hole, thereby achieving concentric positioning between the positioning seat and the machined large hole.

2. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque-limiting structure according to claim 1, characterized in that: The depth-fixing assembly includes a flat plate, a pair of guide rails fixed to the outer wall of the flat plate by bolts, a slide table slidably disposed on the guide rails, a clamp fixed to the slide table by bolts for gripping the electric hammer body, a slide rod fixed to the outer wall of the flat plate by bolts, a first spring sleeved on the outside of the slide rod, a limiting frame slidably disposed on the slide table, and a pair of locking pins threaded to the outer wall of the limiting frame. The bracket on the slide table is slidably sleeved on the outside of the slide rod, and the elastic force provided by the first spring pushes the slide table to move away from the positioning seat.

3. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 2, characterized in that: The depth-fixing component also includes indicator marks on both sides of the limiting frame and two rulers fixed to the outer wall of the plate by screws.

4. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 3, characterized in that: The positioning base also includes a connecting plate fixed to the end of the flat plate by bolts, a protective cover welded to the outer wall of the connecting plate, and an annular cover fixed to the outer wall of the connecting plate by screws. The positioning block is integrally formed at the end of the annular cover.

5. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 4, characterized in that: The positioning seat has a bushing at its center for the drill bit to pass through. The bushing is fixedly connected to the protective cover on the side near the electric hammer by screws. The bushing has a round hole at its center for the drill bit to pass through.

6. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 5, characterized in that: The protective cover has an integrally formed annular plate inside the cavity, and a sliding groove is formed through the annular plate. A through groove is formed on the annular cover for the extrusion block to slide. The positioning seat also includes a discharge pipe that is snapped and fixed between the outer cover body of the protective cover and the annular plate for discharging the dust generated during drilling.

7. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 6, characterized in that: The clamping assembly also includes a pressure rod fixedly connected to the ends of a pair of sliders by bolts, a limiting rod slidably sleeved inside the pressure rod, and several second springs welded to the outer wall of the pressure rod.

8. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 7, characterized in that: The clamping frame is sleeved on the outside of the pressure rod, and the limiting rod is fixedly connected to the clamping frame through the thread at its end. The end of the second spring is sleeved in the groove on the outer wall of the clamping frame, and the elastic force provided by the second spring pushes the clamping frame to move away from the pressure rod.

9. The depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure according to claim 8, characterized in that: The telescopic frame is slidably fitted with a round rod, and a third spring is fitted on the outer side of the round rod. The two ends of the round rod are respectively snapped and fixed to the inside of the ring plate and the inner wall of the protective cover.

10. A method for depth-determinable stepped positioning of concentric drilling within a hole based on a torque limiting structure, using the depth-determinable stepped positioning device for concentric drilling within a hole based on a torque limiting structure as described in claim 9, characterized in that... Includes the following steps: S1. Select a positioning block with a matching outer diameter according to the inner diameter of the machined large hole, put the external connector on the outside of the electric hammer body, and fix it to the electric hammer body by clamping it tightly, so that the slide moves synchronously with the electric hammer body. S2. Slide the limit frame along the slide table. Use the indicator marks on both sides of the limit frame and the scale on the guide rail to read and set the required drilling depth value. Then tighten the locking pin. The end of the locking pin abuts against the surface of the slide table to lock the limit frame on the slide table. S3. Align the positioning block at the end of the positioning seat with and insert it into the machined large hole. The outer wall of the positioning block fits against the inner wall of the large hole to achieve radial positioning of the positioning seat and the machined large hole. Continue to advance the positioning seat until the end face of the annular cover fits against the workpiece surface to achieve axial positioning. S4. During the process of advancing the positioning seat, the extrusion block is squeezed by the end face of the workpiece and shrinks into the positioning seat. The inclined chamfer at the end of the extrusion block pushes the inclined block on the telescopic frame, which drives the telescopic frame to move away from the extrusion block and compresses the third spring. The telescopic frame drives the slider to move synchronously through the round rod. The slider pushes the clamping frame to extend outward through the pressure rod until the clamping frame presses against the wall of the large hole and the pressure rod and the clamping frame form a rigid contact, realizing the double concentric positioning of the positioning seat and the machined large hole. S5. Start the electric hammer. The drill bit passes through the central hole of the bushing. The bushing guides the drill bit radially. Drilling is performed in the center of the large hole. The dust generated during drilling is discharged through the discharge pipe. S6. When the drill bit is fed to the preset drilling depth, the limit frame abuts against the connecting plate of the positioning seat, forcibly stopping the feed and completing the drilling. During the drilling process, when the cutting resistance of the drill bit exceeds the preset threshold of the electric torque limit mechanism inside the electric hammer, the electric torque limit mechanism automatically cuts off the feed. S7. Turn off the electric hammer, remove the drill bit, take the external connector out of the machined large hole, the clamping assembly is reset under the action of the third spring, and the extrusion block extends out of the end face of the positioning seat.

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