A torque limiting mechanism and a variable stroke electric hammer drill

Abstract

This invention relates to a torque limiting mechanism and a variable stroke electric hammer drill. The torque limiting mechanism includes: a housing housing in which a first bevel gear and a second bevel gear are disposed and adapted to each other; an elastic abutment component disposed within the housing housing and connected to the first bevel gear, the elastic abutment component using stored potential energy to cause the first bevel gear to tend to move towards the second bevel gear; and an adjustment component installed within the housing housing, the adjustment component being connected to a lifting member, the lifting member being able to change the potential energy stored in the elastic abutment component. By changing the potential energy stored in the elastic abutment component through the adjustment component, the interaction force between the first and second bevel gears is changed, thereby matching different drill bits and avoiding drill bit breakage due to excessive torque when the drill bit is thin.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric hammer drill, in particular to a torque limiting mechanism and stroke variable electric hammer drill. BACKGROUND

[0002] Electric hammer drill is a hand-held electric tool with two functions of "impact drill" and "electric hammer". The "impact drill" mainly uses rotary cutting and has an impact mechanism driven by impact force to drive the impact drill bit. While driving the drill bit to rotate, there is a reciprocating hammering movement perpendicular to the rotation surface of the drill bit. It is used for drilling holes in materials such as concrete, bricks, tiles, and marble. The "electric hammer" is used for slotting, large hole opening, or breaking concrete in materials such as concrete and bricks.

[0003] The existing electric hammer drill has constant output torque, which makes the electric hammer drill stable during work. However, different specifications of drill bits can withstand different torques. For example, thinner drill bits can only withstand smaller torques. When a thinner drill bit is used, if the torque is large and the drill bit is stuck in the concrete, the drill bit is prone to breakage. SUMMARY

[0004] The purpose of the present application is to provide a torque limiting mechanism and a stroke variable electric hammer drill to solve the problems raised in the background.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] A torque limiting mechanism, comprising:

[0007] An outer shell, wherein a first bevel gear and a second bevel gear are arranged in the outer shell and are adapted to each other;

[0008] An elastic abutting assembly arranged in the outer shell and connected with the first bevel gear, wherein the elastic abutting assembly has a tendency to move towards the second bevel gear by storing potential energy;

[0009] An adjusting assembly installed in the outer shell, wherein a lifting piece is connected to the adjusting assembly, and the lifting piece can change the potential energy stored by the elastic abutting assembly.

[0010] As a further solution of the present application, the elastic abutting assembly comprises a driving shaft rotatably installed in the outer shell, the driving shaft is hollow, and a telescopic shaft is slidably sleeved in the driving shaft, one end of the telescopic shaft away from the driving shaft is connected with the first bevel gear, and the other end is provided with a protrusion penetrating through the driving shaft;

[0011] The lifting piece is sleeved on the driving shaft, and a first spring is sleeved on the driving shaft, one end of the first spring is connected with the protrusion, and the other end is connected with the lifting piece.

[0012] As a further scheme of the present application, the adjusting assembly comprises a sleeve block slidingly arranged on the lifting piece and a guide plate arranged in the outer shell body, the guide plate is provided with a stepped groove, and a first pulley rotatably arranged on the side of the sleeve block can roll in the stepped groove.

[0013] The adjusting assembly further comprises a locking structure connected with the sleeve block.

[0014] As a further scheme of the present application, the locking structure comprises a moving piece slidingly arranged on the outer shell body, and the moving piece is slidingly connected with a follow-up sleeve plate arranged on the sleeve block.

[0015] A pushing shaft is slidingly arranged in the moving piece, one end of the pushing shaft is provided with a protruding shaft penetrating through the moving piece and extending to the outside of the moving piece.

[0016] The locking structure further comprises a plurality of protruding portions arranged on the moving piece, a locking shaft is slidingly arranged on the protruding portions, the locking shaft is matched with an embedded groove arranged on the outer shell body, and an inclined rod matched with the protruding shaft is further arranged on the locking shaft.

[0017] A second spring is further sleeved on the locking shaft, one end of the second spring is connected with the protruding portion, and the other end is connected with a limiting ring arranged on the locking shaft.

[0018] The electric hammer drill with variable stroke further comprises:

[0019] A follow-up assembly is arranged in the outer shell body and connected with the driving shaft, the follow-up assembly can drive a clamping tool slidingly sleeved with the second bevel gear to reciprocate.

[0020] A threaded switching assembly is connected with the follow-up assembly, and the threaded switching assembly can change the stroke of the follow-up assembly driving the clamping tool to reciprocate.

[0021] As a further scheme of the present application, the follow-up assembly comprises a driven shaft rotatably arranged in the outer shell body, the driven shaft is connected with the driving shaft through a toothed belt, one end of the driven shaft is provided with a rotating piece, and the rotating piece is provided with a second pulley.

[0022] The follow-up assembly further comprises a rotating sleeve ring rotatably connected with the clamping tool, two guide tubes are symmetrically arranged on the rotating sleeve ring, and the guide tubes are slidingly matched with guide rods arranged in the outer shell body.

[0023] The clamping tool is further provided with a reciprocating plate, which is provided with a guide groove matched with the second pulley along the length direction of the reciprocating plate.

[0024] As a further scheme of the present application, the thread switching assembly comprises a screw rod rotatably installed on the outer shell, a threaded sleeve threadedly connected with the screw rod, and a connecting piece installed on the threaded sleeve.

[0025] The thread switching assembly further comprises a connecting structure arranged on the driven shaft and connected with the connecting piece and the second pulley.

[0026] As a further scheme of the present application, the connecting structure comprises a lifting sleeve sleeved on the driven shaft, an annular groove rotatably connected with the connecting piece arranged on the lifting sleeve, and a support rod rotatably installed on the lifting sleeve, wherein one end of the support rod away from the lifting sleeve is rotatably installed with a sliding block, the sliding block is rotatably connected with the second pulley, and the sliding block is slidably arranged on the rotating piece.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] Through the elastic abutting assembly and the adjusting assembly, on one hand, when the drill bit is stuck in the concrete, the first bevel gear is separated from the second bevel gear, so as to cut off the transmission between the first bevel gear and the drill bit, thereby avoiding the drill bit breakage caused by excessive torque when the drill bit is stuck in the concrete; on the other hand, by adjusting the initial compression amount of the first spring, the force between the first bevel gear and the second bevel gear can be adjusted, so as to match different types of drill bits, that is, the larger the drill bit, the greater the force between the first bevel gear and the second bevel gear.

[0029] Through the thread switching assembly, the impact stroke of the drill bit is variable, so as to select a suitable impact stroke according to different situations in actual use, thereby improving the applicability of the electric hammer drill. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Structure schematic view of one embodiment of the torque limiting mechanism and stroke variable electric hammer drill;

[0031] Figure 2 Structure schematic view of another angle of one embodiment of the torque limiting mechanism and stroke variable electric hammer drill;

[0032] Figure 3 Structure schematic view of another angle of one embodiment of the torque limiting mechanism and stroke variable electric hammer drill; Figure 2 Structure enlarged schematic view of A in the middle;

[0033] Figure 4Structure diagram of a housing in an embodiment of a torque limiting mechanism and stroke variable electric hammer drill;

[0034] Figure 5 Structure diagram of a elastic abutting assembly and an adjusting assembly in an embodiment of a torque limiting mechanism and stroke variable electric hammer drill;

[0035] Figure 6 Exploded view of the elastic abutting assembly in an embodiment of a torque limiting mechanism and stroke variable electric hammer drill;

[0036] Figure 7 Exploded view of the adjusting assembly in an embodiment of a torque limiting mechanism and stroke variable electric hammer drill;

[0037] Figure 8 Structure diagram of a follow-up assembly and a thread switching assembly in an embodiment of a torque limiting mechanism and stroke variable electric hammer drill;

[0038] In the figure: 1, housing; 2, driving shaft; 3, telescopic shaft; 4, protrusion; 5, first bevel gear; 6, second bevel gear; 7, transmission shaft; 8, clamping tool; 9, first spring; 10, lifting piece; 11, sleeve block; 12, first pulley; 13, guide plate; 14, stepped groove; 15, follow-up sleeve plate; 16, moving piece; 17, pushing shaft; 18, protruding shaft; 19, inclined rod; 20, locking shaft; 21, second spring; 22, fitting groove; 23, toothed belt; 24, driven shaft; 25, rotating piece; 26, sliding block; 27, support rod; 28, connecting piece; 29, threaded sleeve; 30, screw rod; 31, second pulley; 32, reciprocating plate; 33, rotating sleeve ring; 34, lifting sleeve. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] In addition, the elements in the present application are referred to as "fixed to" or "provided on" another element, which can be directly on another element or can have a middle element. When an element is considered to be "connected" to another element, it can be directly connected to another element or can have a middle element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for illustrative purposes, and do not represent the only implementation.

[0041] Please refer to Figures 1-7The torque limiting mechanism in the embodiment of the present application comprises an outer housing 1, an elastic abutting assembly and an adjusting assembly.

[0042] The outer housing 1 is provided with a first bevel gear 5 and a second bevel gear 6 which are adapted to each other;

[0043] The elastic abutting assembly is arranged in the outer housing 1 and connected with the first bevel gear 5, and the elastic abutting assembly makes the first bevel gear 5 have a tendency to move towards the second bevel gear 6 through stored potential energy;

[0044] The adjusting assembly is installed in the outer housing 1, and a lifting piece 10 is connected to the adjusting assembly, and the lifting piece 10 can change the potential energy stored by the elastic abutting assembly;

[0045] The elastic abutting assembly comprises a driving shaft 2 which is rotatably installed in the outer housing 1, the inside of the driving shaft 2 is a hollow structure, and a telescopic shaft 3 is slidably sleeved in the driving shaft 2, one end of the telescopic shaft 3 away from the driving shaft 2 is connected with the first bevel gear 5, and the other end is provided with a protrusion 4 which penetrates the driving shaft 2;

[0046] The lifting piece 10 is sleeved on the driving shaft 2, and a first spring 9 is sleeved on the driving shaft 2, one end of the first spring 9 is connected with the protrusion 4, and the other end is connected with the lifting piece 10;

[0047] The adjusting assembly comprises a sleeve block 11 which is slidably arranged on the lifting piece 10 and a guide plate 13 which is arranged in the outer housing 1, the guide plate 13 is provided with a stepped groove 14, and a first pulley 12 which is rotatably installed on the side of the sleeve block 11 can roll in the stepped groove 14;

[0048] The adjusting assembly further comprises a locking structure connected with the sleeve block 11, and the locking structure comprises a moving piece 16 which is slidably arranged on the outer housing 1 and slidably connected with a follow-up sleeve plate 15 which is installed on the sleeve block 11;

[0049] A pushing shaft 17 is slidably installed in the moving piece 16, and one end of the pushing shaft 17 is provided with a convex shaft 18 which penetrates the moving piece 16 and extends to the outside of the moving piece 16;

[0050] The locking structure further comprises a plurality of protruding parts arranged on the moving piece 16, a locking shaft 20 is slidably installed on the protruding parts, the locking shaft 20 is adapted to an embedded groove 22 arranged on the outer housing 1, and an inclined rod 19 which is adapted to the convex shaft 18 is further arranged on the locking shaft 20;

[0051] The locking shaft 20 is further sleeved with a second spring 21, one end of the second spring 21 is connected with the protruding part, and the other end is connected with a limiting ring arranged on the locking shaft 20.

[0052] In use, the driving shaft 2 rotates, the driving shaft 2 is provided with a long slot along the length direction thereof, and the protrusion 4 is slidingly arranged in the long slot, so that when the driving shaft 2 rotates, the driving shaft 2 can drive the first bevel gear 5 to rotate under the action of the long slot and the protrusion 4, and under the action of the first spring 9, the first bevel gear 5 has a tendency to move towards the second bevel gear 6, under the tendency, the first bevel gear 5 meshes with the second bevel gear 6, thereby driving the drill bit to rotate through the second bevel gear 6, and when the drill bit is stuck in the concrete, the second bevel gear 6 immediately stops rotating, so that the interaction force between the second bevel gear 6 and the first bevel gear 5 increases, at this time, the first bevel gear 5 rotates and is separated from the second bevel gear 6, thereby cutting off the transmission between the first bevel gear 5 and the drill bit, and avoiding the drill bit from being broken due to excessive torque when the drill bit is stuck in the concrete.

[0053] Further, when the moving part 16 is pulled to move, the pushing shaft 17 is first pressed to move by the index finger, so that the convex shaft 18 connected with the pushing shaft 17 moves, the convex shaft 18 cooperates with the inclined rod 19 to drive the locking shaft 20 to separate from the fitting groove 22, and further compress the second spring 21, then the moving part 16 is pulled to move, so that the following sleeve plate 15 sleeved with the moving part 16 moves, the sleeve block 11 arranged on the following sleeve plate 15 moves in the stepped groove 14, so that when the following sleeve plate 15 moves with the moving part 16, the sleeve block 11 moves upward, and the one end of the first spring 9 is compressed by the lifting part 10, so that the action force of the first spring 9 on the telescopic shaft 3 increases, thereby increasing the interaction force between the first bevel gear 5 and the second bevel gear 6.

[0054] Through the above arrangement, on the one hand, when the drill bit is stuck in the concrete, the first bevel gear 5 is separated from the second bevel gear 6, thereby cutting off the transmission between the first bevel gear 5 and the drill bit, and avoiding the drill bit from being broken due to excessive torque when the drill bit is stuck in the concrete, on the other hand, by adjusting the initial compression amount of the first spring 9, the action force between the first bevel gear 5 and the second bevel gear 6 can be adjusted, thereby matching different types of drill bits, that is, the larger the drill bit, the greater the action force between the first bevel gear 5 and the second bevel gear 6.

[0055] Please refer to Figure 4 , Figure 8 , as an embodiment of the present application, a stroke variable electric hammer drill is further provided, which comprises the torque limiting mechanism, and further comprises a following assembly and a threaded switching assembly.

[0056] The follow-up assembly is arranged in the outer casing 1 and connected with the driving shaft 2, the follow-up assembly can drive the clamping tool 8 sleeved with the second bevel gear 6 to reciprocate, in particular, the clamping tool 8 is connected with the transmission shaft 7 coaxial with the second bevel gear 6;

[0057] The follow-up assembly comprises a driven shaft 24 rotatably arranged in the outer casing 1, the driven shaft 24 is connected with the driving shaft 2 through the toothed belt 23, and one end of the driven shaft 24 is provided with a rotating part 25, the rotating part 25 is provided with a second pulley 31;

[0058] The follow-up assembly further comprises a rotating sleeve ring 33 rotatably connected with the clamping tool 8, the rotating sleeve ring 33 is symmetrically provided with two guide pipes, the guide pipes are slidably matched with guide rods arranged in the outer casing 1;

[0059] The clamping tool 8 is further provided with a reciprocating plate 32, the reciprocating plate 32 is provided with a guide groove along the length direction of the reciprocating plate 32, the guide groove is rollingly matched with the second pulley 31;

[0060] The threaded switching assembly is connected with the follow-up assembly, the threaded switching assembly can change the stroke of the reciprocating movement of the clamping tool 8 driven by the follow-up assembly;

[0061] The threaded switching assembly comprises a lead screw 30 rotatably arranged on the outer casing 1, the lead screw 30 is provided with a threaded sleeve 29 threadedly connected with the lead screw 30, and the threaded sleeve 29 is provided with a connecting piece 28;

[0062] The threaded switching assembly further comprises a connecting structure arranged on the driven shaft 24 and connected with the connecting piece 28 and the second pulley 31, the connecting structure comprises a lifting sleeve 34 sleeved on the driven shaft 24, the lifting sleeve 34 is provided with an annular groove rotatably connected with the connecting piece 28, the lifting sleeve 34 is further rotatably provided with a supporting rod 27, one end of the supporting rod 27 away from the lifting sleeve 34 is rotatably provided with a sliding block 26, the sliding block 26 is rotatably connected with the second pulley 31, and the sliding block 26 is slidably arranged on the rotating part 25.

[0063] When the driving shaft 2 rotates, the driving shaft 2 drives the driven shaft 24 connected with the driving shaft 2 to rotate through the toothed belt 23, when the driven shaft 24 rotates, the rotating part 25 makes a circular motion, so that the second pulley 31 arranged on the rotating part 25 makes a circular motion, when the second pulley 31 makes a circular motion, the second pulley 31 is rollingly matched with the guide groove on the reciprocating plate 32, so that the reciprocating plate 32 reciprocates along the length direction of the guide rod, thereby driving the clamping tool 8 to reciprocate, so that the drill bit impacts.

[0064] Further, by rotating the screw rod 30, the threaded sleeve 29 arranged on the screw rod 30 can move along the length direction of the screw rod 30, and the lifting sleeve 34 can be driven to move along the length direction of the driven shaft 24 through the connecting piece 28. Specifically, when the lifting sleeve 34 moves towards the rotating piece 25, the lifting sleeve 34 will drive the sliding block 26 to move away from the driven shaft 24 through the support rod 27, so that the radius of the circumferential motion of the second pulley 31 increases, and the stroke of the reciprocating plate 32 increases.

[0065] Through the above arrangement, the impact stroke of the drill bit can be changed, so that suitable impact stroke can be selected for different situations in actual use, and the applicability of the electric hammer drill is improved.

[0066] As described above, in use, the driving shaft 2 is rotated, the driving shaft 2 is provided with a long groove along the length direction thereof, and the protrusion 4 is slidingly arranged in the long groove, so that when the driving shaft 2 is rotated, the driving shaft 2 can drive the first bevel gear 5 to rotate under the action of the long groove and the protrusion 4, and the first bevel gear 5 has a tendency to move towards the second bevel gear 6 under the action of the first spring 9. Under this tendency, the first bevel gear 5 meshes with the second bevel gear 6, so as to drive the drill bit to rotate through the second bevel gear 6, and when the drill bit is stuck in the concrete, the second bevel gear 6 immediately stops rotating, so that the interaction force between the second bevel gear 6 and the first bevel gear 5 increases, and at this time, the first bevel gear 5 rotates and is separated from the second bevel gear 6, so as to cut off the transmission between the first bevel gear 5 and the drill bit, thereby avoiding the breakage of the drill bit due to excessive torque when the drill bit is stuck in the concrete.

[0067] When the moving piece 16 is pulled to move, the pushing shaft 17 is first pressed to move by the index finger, so that the convex shaft 18 connected with the pushing shaft 17 moves and cooperates with the inclined rod 19 to drive the locking shaft 20 to separate from the fitting groove 22, and further compress the second spring 21. Then, the moving piece 16 is pulled to move, so that the follower sleeve plate 15 sleeved with the moving piece 16 moves, the sleeve block 11 arranged on the follower sleeve plate 15 moves in the stepped groove 14, the sleeve block 11 moves upwards when the follower sleeve plate 15 moves with the moving piece 16, and the one end of the first spring 9 is compressed by the lifting piece 10, so as to increase the acting force of the first spring 9 on the telescopic shaft 3, and increase the interaction force between the first bevel gear 5 and the second bevel gear 6.

[0068] When the driving shaft 2 rotates, the driving shaft 2 will drive the driven shaft 24 connected therewith to rotate through the toothed belt 23, and when the driven shaft 24 rotates, the rotating member 25 can be made to move in a circle, so that the No. 2 pulley 31 arranged on the rotating member 25 moves in a circle, and when the No. 2 pulley 31 moves in a circle, the No. 2 pulley 31 is in rolling fit with the guide groove on the reciprocating plate 32, so as to make the reciprocating plate 32 reciprocate along the length direction of the guide rod, thereby driving the clamping tool 8 to reciprocate and making the drill bit impact.

[0069] By rotating the screw rod 30, the threaded sleeve 29 arranged on the screw rod 30 can be made to move along the length direction of the screw rod 30, and the lifting sleeve 34 is driven to move along the length direction of the driven shaft 24 through the connecting piece 28, specifically, when the lifting sleeve 34 moves towards the rotating member 25, the lifting sleeve 34 will drive the sliding block 26 to move away from the driven shaft 24 through the support rod 27, so as to increase the radius of the No. 2 pulley 31 moving in a circle, so as to increase the stroke of the reciprocating plate 32 reciprocating.

[0070] It is apparent for those skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, and the present application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0071] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A variable stroke hammer drill, characterized by, The torque limiting mechanism comprises: An outer housing (1) is provided with a first bevel gear (5) and a second bevel gear (6) which are adapted to each other; An elastic abutting assembly is arranged in the outer housing (1) and connected with the first bevel gear (5), and the elastic abutting assembly makes the first bevel gear (5) have a tendency to move towards the second bevel gear (6) through stored potential energy; An adjusting assembly is arranged in the outer housing (1), and a lifting piece (10) is connected to the adjusting assembly, and the lifting piece (10) can change the potential energy stored by the elastic abutting assembly; The elastic abutting assembly comprises a driving shaft (2) which is rotatably arranged in the outer housing (1), the inside of the driving shaft (2) is hollow, and a telescopic shaft (3) is slidably arranged in the driving shaft (2), one end of the telescopic shaft (3) away from the driving shaft (2) is connected with the first bevel gear (5), and the other end is provided with a protrusion (4) penetrating through the driving shaft (2); The lifting piece (10) is sleeved on the driving shaft (2), and a first spring (9) is sleeved on the driving shaft (2), one end of the first spring (9) is connected with the protrusion (4), and the other end is connected with the lifting piece (10); The adjusting assembly comprises a sleeve block (11) slidably arranged on the lifting piece (10) and a guide plate (13) arranged in the outer housing (1), the guide plate (13) is provided with a stepped groove (14), and a first pulley (12) rotatably arranged on the side of the sleeve block (11) can roll in the stepped groove (14); The adjusting assembly further comprises a locking structure connected with the sleeve block (11); The locking structure comprises a moving piece (16) slidably arranged on the outer housing (1), and the moving piece (16) is slidably connected with a follow-up sleeve plate (15) arranged on the sleeve block (11); A pushing shaft (17) is slidably arranged in the moving piece (16), and one end of the pushing shaft (17) is provided with a convex shaft (18) penetrating through the moving piece (16) and extending to the outside of the moving piece (16); The locking structure further comprises a plurality of protruding portions arranged on the moving piece (16), a locking shaft (20) is slidably arranged on the protruding portions, the locking shaft (20) is adapted to a fitting groove (22) arranged on the outer housing (1), and an inclined rod (19) adapted to the convex shaft (18) is further arranged on the locking shaft (20); A second spring (21) is further sleeved on the locking shaft (20), one end of the second spring (21) is connected with the protruding portion, and the other end is connected with a limiting ring arranged on the locking shaft (20); The stroke-variable electric hammer drill further comprises: A follow-up assembly is arranged in the outer housing (1) and connected with the driving shaft (2), and the follow-up assembly can drive a clamping tool (8) slidably arranged on the second bevel gear (6) to reciprocate. A threaded switching assembly is connected with the follow-up assembly, and the threaded switching assembly can change the stroke amount of the follow-up assembly driving the clamping tool (8) to reciprocate.

2. The variable stroke hammer drill according to claim 1, wherein The follow-up assembly comprises a driven shaft (24) rotatably installed in the outer shell (1), the driven shaft (24) is connected with the driving shaft (2) through a toothed belt (23), and one end of the driven shaft (24) is provided with a rotating part (25), and the rotating part (25) is provided with a second pulley (31); The follow-up assembly further comprises a rotating sleeve ring (33) rotatably connected with the clamping tool (8), the rotating sleeve ring (33) is symmetrically provided with two guide tubes, and the guide tubes are in sliding fit with guide rods arranged in the outer shell (1); The clamping tool (8) is further provided with a reciprocating plate (32), and the reciprocating plate (32) is provided with a guide groove in rolling fit with the second pulley (31) along the length direction of the reciprocating plate (32).

3. The variable stroke hammer drill according to claim 2, wherein The threaded switching assembly comprises a lead screw (30) rotatably installed on the outer shell (1), the lead screw (30) is provided with a threaded sleeve (29) in threaded connection therewith, and the threaded sleeve (29) is installed with a connecting piece (28). The threaded switching assembly further comprises a connecting structure arranged on the driven shaft (24) and connected with the connecting piece (28) and the second pulley (31).

4. The variable stroke hammer drill according to claim 3, wherein The connecting structure comprises a lifting sleeve (34) sleeved on the driven shaft (24), the lifting sleeve (34) is provided with an annular groove in rotational connection with the connecting piece (28), and the lifting sleeve (34) is further rotatably installed with a supporting rod (27), one end of the supporting rod (27) away from the lifting sleeve (34) is rotatably installed with a sliding block (26), the sliding block (26) is rotatably connected with the second pulley (31), and the sliding block (26) is slidably arranged on the rotating part (25).

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