Height-adjustable crane pipe

Abstract

The utility model discloses a height-adjustable crane pipe, and relates to the field of crane pipe equipment. The height-adjustable loading arm comprises a spring cylinder, wherein the spring cylinder comprises a pull rod, a sleeve and a main springback assembly; the auxiliary springback assembly comprises a shell, auxiliary springs, a sliding rail and a pulley, the shell is fixedly connected with the sleeve, the auxiliary springs are fixedly arranged on the inner wall of the shell, the sliding rail is arranged on the auxiliary springs in the moving direction of the pull rod, the pulley is arranged on the abutting face of the sliding rail and fixedly connected with the pull rod, the abutting face is an inclined face, one end of the abutting face is close to the pull rod, and the other end of the abutting face is close to the sliding rail. The other end is far away from the pull rod; when the pull rod moves in the direction of increasing the elastic force of the main rebound assembly, the pulley moves towards the end, close to the pull rod, of the abutting face. The auxiliary springback assembly enables the elastic force provided by the main springback assembly to be reduced, and the reduction degree can be changed, so that under the condition that the height of a pipeline of the crane pipe is changed, the service life of the interface flange of the crane pipe and the service life of the interface flange of a tank car are prolonged, and the sealing performance is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to crane pipe equipment field, especially crane pipe with adjustable height. BACKGROUND

[0002] Crane pipe is a telescopic pipe, mainly used for loading and unloading liquid in oil and chemical wharf. Compared with the old hose, crane pipe has higher safety, flexibility and service life, so it is known as the special equipment in the fluid loading and unloading process of petrochemical industry.

[0003] In the prior art crane pipe technology, as shown in Figure 1 The pipeline of the crane pipe is provided with a balancer, which is generally a gas cylinder, a hydraulic cylinder or a spring cylinder. When the spring cylinder is used as the balancer, the specific structure is that the spring cylinder connecting plate is fixed, one end of the pipeline and the spring cylinder connecting plate is rotatably connected, the pull rod of the spring cylinder and the other end of the spring cylinder connecting plate are connected through a first hinge, and a second hinge is fixedly arranged at the middle section of the pipeline. The balancer offsets the gravity of the pipeline, avoids that the interface flange of the crane pipe and the tank truck interface bear large stress, and reduces the service life and sealing performance of the interface flanges of the crane pipe and the tank truck.

[0004] However, when the spring cylinder is used as the balancer in the prior art crane pipe technology, the problem is that when the interface flange of the crane pipe needs to be connected to different vehicles, the height of the connection changes, so the height of the end of the pipeline close to the interface flange needs to be adjusted. When the pipeline is lifted upward, the pull rod needs to be retracted into the inside of the spring cylinder sleeve, so that the entire spring cylinder is shortened. At this time, the elastic force provided by the spring cylinder is reduced, and the problem that the elastic force is not enough to offset the gravity of the pipeline exists, so that the pipeline is pre-inclined downward, which generates a downward force on the interface connection. When the pipeline is pressed downward, the pull rod needs to be extended out of the inside of the spring cylinder sleeve, so that the entire spring cylinder is lengthened. At this time, the elastic force provided by the spring cylinder is increased, and even after the elastic force offsets the gravity of the pipeline, there is still residual elastic force of the spring, which pulls the pipeline upward, so that the pipeline is pre-lifted upward, which generates an upward force on the interface connection. Therefore, after the height of the pipeline changes, the service life and sealing performance of the interface flanges of the crane pipe and the tank truck are reduced. TECHNICAL PROBLEM

[0005] In view of the defects in the prior art, the technical problem solved by the utility model is how to improve the service life and sealing performance of the interface flanges of the crane pipe and the tank truck when the height of the pipeline changes.

[0006] To achieve the above purpose, the utility model provides a crane pipe with adjustable height, which comprises:

[0007] The spring cylinder comprises a pull rod, a sleeve and a main rebound assembly, the pull rod is arranged in the interior of the sleeve, one end of the pull rod is located outside the sleeve, the other end of the pull rod is fixedly provided with a baffle, the main rebound assembly is sleeved on the pull rod, and one end of the main rebound assembly abuts against the baffle, and the other end of the main rebound assembly abuts against the inner end of the sleeve;

[0008] The auxiliary rebound assembly comprises an outer shell, an auxiliary spring, a sliding rail and a pulley, the outer shell is fixedly connected with the sleeve, a plurality of auxiliary springs are fixedly arranged on the inner wall of the outer shell, the sliding rail is arranged on the auxiliary spring in the moving direction of the pull rod, the pulley is arranged on the abutting surface of the sliding rail, and the pulley is fixedly connected with the pull rod, the abutting surface is an inclined surface, one end of the abutting surface is close to the pull rod, and the other end of the abutting surface is away from the pull rod;

[0009] When the pull rod moves in the direction of increasing the elastic force of the main rebound assembly, the pulley moves to the end of the abutting surface close to the pull rod.

[0010] By adopting the above technical scheme, when the pull rod is stretched or retracted, the degree of the auxiliary rebound assembly to offset the elastic force of the main rebound assembly changes with the movement of the pull rod, so that the crane pipe is always in a balanced state. Therefore, the service life and sealing performance of the interface flange of the crane pipe and the tank truck interface flange are improved in the case that the height of the pipeline changes.

[0011] In combination with the first aspect, in an implementation mode, the baffle is provided with a baffle adjusting assembly, the adjusting assembly comprises a thread arranged on the pull rod and a nut abutting against the baffle, the nut is threadedly connected to the pull rod, and the thread is used to adjust the position of the baffle on the pull rod.

[0012] By adopting the above technical scheme, because the nut abuts against one side of the baffle and the nut is threadedly connected to the pull rod, the nut can be moved on the pull rod by screwing the nut, thereby driving the baffle to move on the pull rod, that is, the position of the baffle on the pull rod is changed. Because the baffle abuts against the main rebound assembly, the initial elastic force of the main rebound assembly is changed. At the same time, the baffle drives the pulley to move on the sliding rail, so the initial elastic force of the auxiliary spring is also changed. The position of the baffle on the pull rod can be adjusted according to actual requirements, thereby improving the applicability of the crane pipe.

[0013] In an implementation mode, one side of the sliding rail provided with the auxiliary spring is provided with a plurality of support rods, one end of the support rod is fixed to the sliding rail, the other end of the support rod is inserted into the interior of the auxiliary spring, and there is always a gap between the other end of the support rod and the inner wall of the outer shell.

[0014] By adopting the above technical scheme, the middle part of the auxiliary spring is prevented from bending to the side when the auxiliary spring is compressed, so the support rod is installed on the sliding rail to realize normal compression of the auxiliary spring along the support rod.

[0015] In one embodiment, the number of the supporting rods is the same as that of the secondary springs.

[0016] Alternatively, the number of the supporting rods is different from that of the secondary springs.

[0017] By adopting the above technical solution, it can be determined whether the secondary spring needs to be sleeved on the supporting rod according to actual requirements and design conditions.

[0018] In one embodiment, the sleeve is provided with a sliding groove in the moving direction of the pull rod, the baffle is fixedly connected with the pulley through a connecting rod, and the connecting rod is movably arranged in the sliding groove.

[0019] By adopting the above technical solution, the relative static state between the pulley and the pull rod can be maintained, and the normal work of the main rebound assembly is not affected by the structure design.

[0020] In one embodiment, the plurality of pulleys are uniformly arranged on the baffle, and the number of the sliding grooves is the same as that of the connecting rods.

[0021] By adopting the above technical solution, the number of the secondary rebound assemblies can be designed according to actual requirements and design conditions. The more the number of the secondary rebound assemblies, the greater the degree of reducing the elastic force provided by the main rebound assembly, and the force of the pull rod received by the secondary rebound assembly is uniform. However, it is necessary to satisfy that the number of the sliding grooves is the same as that of the connecting rods, so as to realize the normal movement of the baffle driving the pulley, thereby further improving the applicability of the crane pipe.

[0022] In one embodiment, the main rebound assembly comprises a plurality of main springs, and a plurality of blocking rings are arranged on the pull rod in the axial direction, and the main spring is arranged between two adjacent blocking rings.

[0023] By adopting the above technical solution, different types of main springs can be placed between two adjacent blocking rings to meet more requirements. Meanwhile, if the baffle adjusting assembly is arranged on this basis, only the initial elastic force of the main spring arranged between the baffle and the closest blocking ring will be affected, so that more subtle adjustment can be made.

[0024] In one embodiment, the main spring is arranged between the baffle and the closest blocking ring.

[0025] Alternatively, there is no main spring between the baffle and the closest blocking ring.

[0026] By adopting the above technical solution, it can be determined whether the main spring is installed between the baffle and the closest blocking ring according to actual requirements and design conditions.

[0027] In one embodiment, the pulley is a concave wheel, the slide rail is provided with a convex boss matched with the concave wheel, and the concave wheel and the convex boss are concave-convex connected.

[0028] By adopting the technical scheme, the connection between the pulley and the slide rail is more stable when the pulley moves on the slide rail, and the pulley is prevented from falling off the slide rail.

[0029] To sum up, the utility model has at least one of the following beneficial technical effects:

[0030] 1. Through the structural design of the auxiliary rebound assembly, the rebound force of the auxiliary spring acting on the pulley can be divided into a thrust along the axis direction of the pull rod and a clamping force of the pulley close to the baffle, the thrust along the axis direction promotes the baffle to move to the inside of the sleeve, that is, promotes the elastic force provided by the main rebound assembly to decrease, thereby solving the problem that the pipeline generates an upward or downward force after height adjustment, and therefore the service life and sealing performance of the interface flange of the crane pipe and the interface flange of the tank car are improved in the case that the height of the pipeline changes.

[0031] 2. The thrust along the axis direction changes with the selection of different models and quantities of the auxiliary spring and the slope design of the slide rail slope, and the above variables can be designed according to actual requirements to meet more use requirements, thereby improving the applicability of the crane pipe. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structural schematic view of a crane pipe with a spring cylinder as a balancer in the related art;

[0033] Figure 2 It is a structural schematic view of a height-adjustable crane pipe according to an embodiment of the utility model;

[0034] Figure 3 It is a structural schematic view of a spring cylinder according to an embodiment of the utility model;

[0035] Figure 4 It is Figure 3 a perspective view.

[0036] In the figure: 1 is a support, 2 is a pipeline, 3 is a spring cylinder connecting plate, 4 is a spring cylinder, 401 is a pull rod, 402 is a sleeve, 403 is a sliding groove, 404 is a main spring, 405 is a stop ring, 406 is a baffle, 407 is a nut, 408 is a thread, 5 is a first hinge, 6 is a second hinge, 7 is a rotating pipeline joint, 8 is an auxiliary rebound assembly, 801 is an outer shell, 802 is a supporting rod, 803 is an auxiliary spring, 804 is a slide rail, 805 is a pulley, 806 is a connecting rod, and 9 is an interface flange. DETAILED DESCRIPTION

[0037] The embodiments of the utility model will be further described in detail below with reference to the drawings.

[0038] The height-adjustable crane pipe in the embodiment of the utility model, referring to Figures 2-4As shown, the height-adjustable crane pipe includes a spring cylinder 4, which comprises a pull rod 401, a sleeve 402, a main rebound assembly and a secondary rebound assembly 8, the pull rod 401 is movably arranged in the inside of the sleeve 402, and the end of the pull rod 401 close to the spring cylinder connecting plate 3 is located outside the sleeve 402, the other end of the pull rod 401 is fixedly provided with a baffle 406, the main rebound assembly is sleeved on the pull rod 401, and one end of the main rebound assembly abuts against the baffle 406, and the other end abuts against the inner end of the sleeve 402, and the secondary rebound assembly 8 is arranged on the baffle 406;

[0039] The secondary rebound assembly 8 comprises an outer shell 801, a secondary spring 803, a sliding rail 804 and a pulley 805, the outer shell 801 is sleeved on the end of the sleeve 402 away from the spring cylinder connecting plate 3, the sleeve 402 is provided with a sliding groove 403 in the axial direction, the baffle 406 is fixedly connected with the pulley 805 through a connecting rod 806, and the connecting rod 806 is movably penetrated on the sliding groove 403, the inner wall of the outer shell 801 is provided with the sliding rail 804 through a plurality of secondary springs 803, the pulley 805 is rollably arranged on the sliding rail 804, and the sliding rail 804 has a slope surface from low to high, and the slope surface of the sliding rail 804 away from the spring cylinder connecting plate 3 is the lowest, and the slope surface of the sliding rail 804 close to the spring cylinder connecting plate 3 is the highest.

[0040] Therefore, on the basis of the existing spring cylinder 4, which offsets the gravity of the pipeline 2 through the pull rod 401, the sleeve 402 and the main rebound assembly, the outer shell 801 of the secondary rebound assembly 8 is arranged at the end of the sleeve 402 away from the spring cylinder connecting plate 3, the sliding rail 804 is arranged on the inner wall of the outer shell 801 through the secondary spring 803, the pulley 805 is movably arranged on the sliding rail 804, and the non-rolling part of the pulley 805 is fixedly connected with the baffle 406 through the connecting rod 806, and the connecting rod 806 penetrates through the sliding groove 403 arranged on the sleeve 402, so that when the baffle 406 moves in the sleeve 402, the pulley 805 moves on the sliding rail 804, and because the sliding rail 804 has a slope surface from low to high, the length of the connecting rod 806 does not change during the movement of the pulley 805 on the sliding rail 804, so that the secondary spring 803 between the sliding rail 804 and the outer shell 801 is squeezed, the secondary spring 803 generates a rebound force, the rebound force acting on the pulley 805 can be divided into an axial direction thrust of the pull rod 401 and a clamping force of the pulley 805 close to the baffle 406, the axial direction thrust promotes the baffle 406 to move to the inside of the sleeve 402, that is, the elastic force provided by the main rebound assembly is reduced, so that the axial direction thrust and the main rebound assembly jointly act to offset the gravity of the pipeline 2, and the axial direction thrust changes with different types and quantities of the secondary spring 803 and the slope design of the slope surface of the sliding rail 804.

[0041] Therefore, when the pipe 2 is lifted upward, although the elastic force provided by the main elastic assembly is reduced, the degree of reduction of the elastic force provided by the main elastic assembly is reduced by the auxiliary elastic assembly 8, so that the elastic force provided by the main elastic assembly is sufficient to offset the gravity of the pipe 2 at present, avoiding that the pipe 2 is subjected to downward force, resulting in downward force on the interface connection; when the pipe 2 is pressed downward, although the elastic force provided by the main elastic assembly is increased, the degree of reduction of the elastic force provided by the main elastic assembly is increased by the auxiliary elastic assembly 8, so that the elastic force provided by the main elastic assembly is only enough to offset the gravity of the pipe 2 at present, avoiding that the pipe 2 is subjected to upward force, resulting in upward force on the interface connection. Therefore, the height of the pipe 2 is changed, the service life and sealing performance of the interface flange 9 of the crane pipe and the interface flange 9 of the tank car are improved.

[0042] Preferably, referring to Figure 2 As shown, the height-adjustable crane pipe further comprises a support 1, a rotating pipe joint 7, a pipe 2 and an interface flange 9, the pipe 2 is fixedly installed on the support 1, two adjacent pipes 2 are connected through the rotating pipe joint 7, and the pipe 2 and the interface flange 9 are connected through the rotating pipe joint 7, the rotating pipe joint 7 is provided with a spring cylinder connecting plate 3, the spring cylinder connecting plate 3 is connected with a pull rod 401 of a spring cylinder 4 through a first hinge 5, a middle section of the pipe 2 is fixedly provided with a second hinge 6, and the second hinge 6 is rotatably connected with a middle section of the spring cylinder 4.

[0043] Preferably, referring to Figure 4 As shown, the baffle 406 is provided with a baffle 406 adjusting assembly, the adjusting assembly comprises a screw thread 408 opened on the pull rod 401 and a nut 407 abutting against the baffle 406, the nut 407 is threadedly connected to the pull rod 401, and the screw thread 408 is used to adjust the position of the baffle 406 on the pull rod 401.

[0044] Specifically, the nut 407 abuts against the side of the spring cylinder connecting plate 3 away from the baffle 406, and the nut 407 is threadedly connected to the pull rod 401, the nut 407 is screwed clockwise or counterclockwise to move the nut 407 on the pull rod 401, thereby moving the baffle 406 on the pull rod 401, that is, changing the position of the baffle 406 on the pull rod 401, and because the baffle 406 abuts against the main elastic assembly, the initial elastic force of the main elastic assembly is changed, at the same time, the baffle 406 drives the pulley 805 to move on the slide rail 804, so that the initial elastic force of the auxiliary spring 803 is also changed, and the position of the baffle 406 on the pull rod 401 can be adjusted according to actual needs, thereby improving the applicability of the crane pipe.

[0045] Preferably, referring to Figure 4As shown, one side of the slide rail 804 provided with the vice spring 803 is provided with a plurality of support rods 802, one end of the support rod 802 is fixed on the slide rail 804, the other end of the support rod 802 is inserted into the inside of the vice spring 803, and there is always a gap between the other end of the support rod 802 and the inner wall of the shell 801.

[0046] Specifically, a plurality of support rods 802 are installed on the slide rail 804, the support rod 802 is oriented in the same direction as the vice spring 803, and one vice spring 803 is sleeved on one support rod 802, which avoids the middle part of the vice spring 803 from bending to the side when the vice spring 803 is compressed, so that the support rod 802 plays a guiding role for the vice spring 803, so that the vice spring 803 can be normally compressed along the support rod 802; at the same time, there is always a gap between the other end of the support rod 802 and the inner wall of the shell 801, that is, no matter how the vice spring 803 is compressed, the other end of the support rod 802 will not contact the inner wall of the shell 801, so it will not affect the compression degree of the vice spring 803, and only plays a guiding role, so the length of the support rod 802 can be designed according to requirements.

[0047] Further, the number of support rods 802 is the same as that of vice springs 803.

[0048] Alternatively, the number of support rods 802 is different from that of vice springs 803.

[0049] Specifically, whether the vice spring 803 needs to be sleeved on the support rod 802 can be determined according to actual requirements and design conditions, for example, there are 5 vice springs 803 in total, 3 of which have support rods 802 inserted inside, and the other 2 vice springs 803 can be arranged between the 3 support rods 802 or not, so as to improve the applicability of the crane pipe.

[0050] Preferably, the vice spring assembly 8 has multiple groups, and the number of slide grooves 403 is the same as the number of groups of vice spring assemblies 8.

[0051] Specifically, the vice spring assembly 8 is provided with two groups, and it should be noted that the number of shells 801 is always one, that is, the two groups of vice springs 803, slide rails 804 and pulleys 805 are installed on the same shell 801, and the number of slide grooves 403 needs to be the same as the number of groups of pulleys 805 to avoid that the pulley 805 cannot work normally; the number of vice spring assemblies 8 can be designed according to actual requirements and design conditions, and the more the number of vice spring assemblies 8, the greater the degree of reducing the elastic force provided by the main spring assembly, but the number of slide grooves 403 must be the same as the number of groups of vice spring assemblies 8 to realize the normal movement of the pulley 805 driven by the baffle 406, thereby further improving the applicability of the crane pipe.

[0052] Preferably, referring toFigure 4 As shown, the main rebound assembly includes a plurality of main springs 404, and a plurality of stop rings 405 are arranged on the pull rod 401 along the axial direction thereof, and the main spring 404 is arranged between two adjacent stop rings 405.

[0053] Specifically, the main rebound assembly includes three main springs 404, which are referred to as the first main spring 404, the second main spring 404 and the third main spring 404, and two stop rings 405 are arranged on the pull rod 401 along the axial direction thereof, which are referred to as the first stop ring 405 and the second stop ring 405, the first main spring 404 is arranged between the first stop ring 405 and the inner end of the sleeve 402, the second main spring 404 is arranged between the first stop ring 405 and the second stop ring 405, and the third main spring 404 is arranged between the second stop ring 405 and the baffle 406; the first main spring 404, the second main spring 404 and the third main spring 404 can be of the same type or different types to meet more requirements, and meanwhile, if the baffle 406 adjusting assembly is arranged on this basis, it will only affect the initial elastic force of the main spring 404 arranged between the baffle 406 and the stop ring 405 closest to the baffle 406, so that more subtle adjustment can be made.

[0054] Further, the main spring 404 is arranged between the baffle 406 and the stop ring 405 closest to the baffle 406.

[0055] Alternatively, the main spring 404 is not arranged between the baffle 406 and the stop ring 405 closest to the baffle 406.

[0056] Specifically, whether the main spring 404 is arranged between the baffle 406 and the stop ring 405 closest to the baffle 406 can be determined according to actual requirements and design conditions, that is, whether the initial elastic force of the main spring 404 will be affected if the baffle 406 adjusting assembly is arranged.

[0057] Preferably, the pulley 805 is a concave pulley, and the sliding rail 804 is provided with a convex boss matched with the concave pulley, and the concave pulley and the convex boss are connected in a concave-convex manner.

[0058] Specifically, the middle part of the pulley 805 is slotted along the circumference thereof, and the slot is matched with the convex boss of the sliding rail 804, and this design makes the connection between the pulley 805 and the sliding rail 804 more stable when the pulley 805 moves on the sliding rail 804, thereby avoiding the pulley 805 from falling off the sliding rail 804.

[0059] The above is merely a specific implementation of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A height-adjustable loading arm, characterized in that It includes: The spring cylinder (4) includes a pull rod (401), a sleeve (402) and a main rebound assembly, the pull rod (401) is arranged in the sleeve (402), one end of the pull rod (401) is located outside the sleeve (402), the other end of the pull rod (401) is fixedly provided with a baffle (406), the main rebound assembly is sleeved on the pull rod (401), and one end of the main rebound assembly abuts against the baffle (406), and the other end abuts against the inner end of the sleeve (402); The secondary rebound assembly (8) includes a shell (801), a secondary spring (803), a sliding rail (804) and a pulley (805), the shell (801) is fixedly connected with the sleeve (402), a plurality of secondary springs (803) are fixedly arranged on the inner wall of the shell (801), the sliding rail (804) is arranged on the secondary spring (803) in the moving direction of the pull rod (401), the pulley (805) is arranged on the abutting surface of the sliding rail (804), and the pulley (805) is fixedly connected with the pull rod (401), the abutting surface is an inclined surface, one end of the abutting surface is close to the pull rod (401), and the other end is away from the pull rod (401); When the pull rod (401) moves in the direction of increasing the elastic force of the main rebound assembly, the pulley (805) moves to the end of the abutting surface close to the pull rod (401).

2. The height adjustable lance of claim 1, wherein: The baffle (406) is provided with a baffle (406) adjusting assembly, the adjusting assembly includes a screw thread (408) formed on the pull rod (401) and a nut (407) abutting against the baffle (406), the nut (407) is threadedly connected to the pull rod (401), and the screw thread (408) is used to adjust the position of the baffle (406) on the pull rod (401).

3. The height adjustable lance of claim 1, wherein: One side of the sliding rail (804) provided with the secondary spring (803) is provided with a plurality of supporting rods (802), one end of the supporting rod (802) is fixed to the sliding rail (804), the other end of the supporting rod (802) is inserted into the secondary spring (803), and there is always a gap between the other end of the supporting rod (802) and the inner wall of the shell (801).

4. The height-adjustable crane pipe according to claim 3, wherein: The number of the supporting rods (802) is the same as that of the secondary springs (803); Or, the number of the supporting rods (802) is different from that of the secondary springs (803).

5. The height adjustable hose according to claim 1, wherein: The sleeve (402) is provided with a sliding groove (403) in the moving direction of the pull rod (401), the baffle (406) is fixedly connected with the pulley (805) through a connecting rod (806), and the connecting rod (806) is movably penetrated in the sliding groove (403).

6. The height adjustable lance of claim 5, wherein: A plurality of pulleys (805) are uniformly arranged around the baffle (406), and the number of the sliding grooves (403) is the same as that of the connecting rods (806).

7. The height adjustable hose ramp of claim 1, wherein: The main rebound assembly includes a plurality of main springs (404), a plurality of baffle rings (405) are arranged on the pull rod (401) in the axial direction, and the main spring (404) is arranged between two adjacent baffle rings (405).

8. The height-adjustable crane pipe according to claim 7, wherein: A main spring (404) is arranged between the baffle plate (406) and its closest baffle ring (405); Or, there is no main spring (404) between the baffle plate (406) and its closest baffle ring (405).

9. The height-adjustable lance of claim 1, wherein: The pulley (805) is a concave wheel, and a convex boss matching the concave wheel is arranged on the slide rail (804), and the concave wheel and the convex boss are connected in concave-convex mode.

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