Weighing apparatus calibration device and calibration method

Abstract

The invention relates to a weighing apparatus calibration device and method, and the device comprises a vehicle frame provided with walking wheels, the vehicle frame is provided with calibration units corresponding to the walking wheels in number one by one, each calibration unit comprises a rotating sleeve located at the front side of the corresponding walking wheel, the rotating axis of the rotating sleeve extends in the vertical direction, and the rotating sleeve is driven by a rotating sleeve driving mechanism. The calibration unit further comprises a lifting winding drum connected with the upper end of the transmission shaft through a pull rope, the bottom of the transmission shaft is fixedly provided with a calibration frame, the calibration frame is provided with a standard weighing sensor used for rolling of the corresponding walking wheel, and the lifting winding drum is connected with the lifting winding drum through a pull rope. When the lifting drum lowers the transmission shaft, the transmission shaft can be separated from the bottom of the rotating sleeve. The invention provides the weighing apparatus calibration device which can complete calibration of the weighing apparatus without hoisting equipment and the calibration method using the weighing apparatus calibration device.

Description

Technical Field

[0001] The present invention relates to the field of verification and calibration, and in particular to a weighing instrument calibration device and a calibration method. Background Art

[0002] A floor scale is a common weighing instrument used to weigh vehicles. It includes a weighing platform for the vehicle to roll over in the front and rear directions. A weighing sensor is arranged on the lower side of the weighing platform. When an empty or fully loaded car passes through the floor scale, the weighing sensor can detect the weight of the car.

[0003] According to the corresponding verification specifications, the weighing sensor of the floor scale needs to be calibrated regularly. The calibration method in the prior art is to move multiple standard weights to the weighing table. Since the weights are relatively heavy, a single weight is 2000kg or 1000kg, and the weight movement process also requires the use of corresponding lifting equipment, that is, using the lifting equipment to move the weights one by one to the weighing table. After the calibration of the weighing sensor is completed, the lifting equipment is used to move the weights one by one from the weighing table.

[0004] Not only does the entire calibration process require the use of lifting equipment, which is very troublesome, but the staff also need to use vehicles to transport the weights to the calibration site. The weights are also transported to the vehicle using lifting equipment, which not only reduces the calibration efficiency but also leads to high calibration costs. Summary of the invention

[0005] The object of the present invention is to provide a weighing instrument calibration device which can complete the calibration of the weighing instrument without the aid of lifting equipment; the object of the present invention is also to provide a calibration method using the weighing instrument calibration device.

[0006] In order to solve the above technical problems, a technical solution of a weighing instrument calibration device in the present invention is as follows: A weighing instrument calibration device comprises a frame provided with running wheels, the frame is provided with calibration units corresponding to the number of running wheels, each calibration unit comprises a rotating sleeve whose rotating axis extends in the up-down direction and is located in front of the corresponding running wheel, the rotating sleeve is driven by a rotating sleeve driving mechanism, a transmission shaft is installed in the rotating sleeve along the up-down direction for guiding movement, the transmission shaft is engaged with the rotating sleeve for stopping rotation, the calibration unit also comprises a lifting drum connected to the upper end of the transmission shaft by a pull rope, a calibration frame is fixed to the bottom of the transmission shaft, a standard weighing sensor for corresponding running wheels to crush is arranged on the calibration frame, when the lifting drum lowers the transmission shaft, the transmission shaft can escape from the bottom of the rotating sleeve.

[0007] Furthermore, the transmission shaft is fixed to one end of the calibration frame.

[0008] Furthermore, the upper end of the transmission shaft has a tapered guide section that is smaller at the top and larger at the bottom, and the pull rope is connected to the top of the tapered guide section.

[0009] Furthermore, the calibration frame has an installation hole that penetrates the calibration frame in the up-down direction, the standard weighing sensor is adapted to be arranged in the installation hole, a sensor limit rod is installed on the calibration frame for guiding movement in the front-to-back direction, the standard weighing sensor is provided with a limit rod socket that cooperates with the sensor limit rod, the calibration frame is provided with a limit rod reset spring that applies a forward force to the sensor limit rod, a walking wheel crushing pedal is hinged on the rear side of the standard weighing sensor on the calibration frame, a walking wheel reset spring is provided on the lower side of the walking wheel crushing pedal, the walking wheel crushing pedal is transmission-connected with the sensor limit rod, when the walking wheel crushing pedal is crushed from back to front by the corresponding walking wheel, the sensor limit rod moves backward and comes out of the limit rod socket; when the walking wheel crushing pedal is crushed from front to back by the corresponding walking wheel, the sensor limit rod moves forward so that the front end of the sensor limit rod is inserted into the limit rod socket.

[0010] Furthermore, the walking wheel rolling pedal and the fiber rod are connected through a ratchet pawl transmission mechanism, the ratchet pawl transmission mechanism includes a ratchet wheel coaxially arranged with the walking wheel rolling pedal, the ratchet pawl transmission mechanism also includes a driving pawl and a braking pawl cooperating with the ratchet wheel, the driving pawl is arranged on the walking wheel rolling pedal, the ratchet pawl transmission mechanism also includes a transmission wheel coaxially arranged with the ratchet wheel, the transmission wheel is provided with transmission tooth segments and optical axis segments in sequence along the circumferential direction, the rear end of the sensor limit rod is provided with a rack for meshing with the transmission tooth segment, the walking wheel rolling pedal is rolled once, and the transmission wheel rotates to realize the switching of the transmission tooth segment, the optical axis segment and the rack.

[0011] Furthermore, a fixed pedal is arranged on the front side of the walking wheel rolling pedal, and a brake pawl is arranged on the fixed pedal.

[0012] The technical solution of the calibration method in the present invention is: The method comprises the following steps: a first step, a frame is moved to a weighing platform of a weighing instrument to be calibrated via running wheels; a second step, a rotating sleeve rotates with a transmission shaft and a calibration frame, so that a standard load cell is located at the front side of a corresponding running wheel, and the transmission shaft is located at the left or right side of the corresponding running wheel; a third step, a lifting drum lowers the calibration frame via a pull rope until the calibration frame falls on the weighing platform; a fourth step, the pull rope continues to be lowered, the frame moves forward, the calibration frame remains stationary relative to the weighing platform, each running wheel respectively moves to a standard load cell of a corresponding calibration unit, and the load cell of the weighing instrument to be calibrated is calibrated by the sum of the readings of each standard load cell; a fifth step, after the calibration is completed, the running wheels move backward, the running wheels are removed from the corresponding standard load cell, the rotating sleeve moves to the upper side of the corresponding transmission shaft, the lifting drum lifts the corresponding transmission shaft via the pull rope, and the transmission shaft returns to the corresponding rotating sleeve.

[0013] The beneficial effects of the present invention are as follows: in the present invention, there is no need to use lifting equipment, and the frame only needs to be moved to the weighing table of the scale to be calibrated by using the walking wheels, and the weighing sensor of the scale can be calibrated by using the weight of the frame. However, the difficulty lies in how to accurately obtain the weight of the frame. In the present invention, the standard weighing sensor can be rotated to the front side of the corresponding walking wheel by rotating the rotating sleeve, and the transmission shaft is located on the left or right side of the walking wheel to prevent the transmission shaft from affecting the forward movement of the walking wheel. The transmission shaft is lowered and disengaged from the rotating sleeve, and the bottom of the calibration frame contacts the weighing table. By placing more pull ropes, the calibration frame can be kept relatively motionless when the frame moves forward, so that the walking wheel can move to the corresponding standard weighing sensor, and the weight of the frame can be measured by the standard weighing sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 It is a usage state diagram of an embodiment of a weighing instrument calibration device in the present invention; Figure 2 yes Figure 1 Schematic diagram of the state after the calibration frame is lowered; Figure 3 yes Figure 1 A top view of the middle calibration frame and the transmission shaft; Figure 4 yes Figure 2 Schematic diagram of the coordination between the calibration frame and the transmission shaft; Figure 5 yes Figure 4 A top view of the alignment frame and the transmission shaft; Figure 6 It is a schematic diagram of the state when the traveling wheel in the present invention travels onto the corresponding standard weighing sensor; Figure 7 yes Figure 1 A in the enlarged view; Figure 8 yes Figure 4 A schematic diagram of the structure of the middle ratchet and pawl transmission mechanism; 1. Weighing platform; 2. Frame; 3. Traveling wheel; 4. Calibration unit; 5. Pull rope; 6. Rotating sleeve; 7. Drive shaft; 8. Calibration frame; 9. Motor; 10. Conical guide section; 11. Reversing pulley; 12. Lifting drum; 13. Standard weighing sensor; 14. Traveling wheel rolling pedal; 15. Fixed pedal; 16. Pedal reset spring; 17. Ratchet and pawl transmission mechanism; 18. Transmission wheel; 19. Ratchet; 20. Rack; 21. Sensor limit rod; 22. Limit rod reset spring; 23. Limit rod jack; 24. Transmission gear segment; 25 Optical axis segment; 26. Driving pawl; 27. Braking pawl; 28. Spring leaf. DETAILED DESCRIPTION

[0015] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. Preferred embodiments of the present invention are provided in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0016] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0017] An embodiment of a weighing instrument calibration device of the present invention is as follows: Figures 1 to 8 As shown: The calibration object of the weighing instrument calibration device in the present invention is a floor scale, which includes a weighing platform 1 and a weighing sensor arranged on the lower side of the weighing platform. The floor scale belongs to the prior art and its structure will not be described in detail here.

[0018] The scale calibration device includes a frame 2 provided with running wheels. In this embodiment, there are four running wheels 3, one pair of which are driving wheels located in the front and driven by a motor, and the other pair of which are follower wheels located in the rear. A counterweight is fixed on the frame.

[0019] The frame is provided with calibration units 4 corresponding to the number of running wheels. The structures of the calibration units 1 are the same, so only one calibration unit and the corresponding running wheel are introduced.

[0020] The calibration units all include a rotating sleeve 6 whose rotating axis extends in the up-down direction along the front side of the corresponding walking wheel. The rotating sleeve is driven by a rotating sleeve driving mechanism. The rotating sleeve driving mechanism includes a motor 9, which is connected to the rotating sleeve through a gear pair. Specifically, the upper end of the rotating sleeve 6 protrudes from the frame, and the gear pair includes a motor shaft gear arranged on the motor shaft of the motor. The gear pair also includes a rotating sleeve gear arranged at the upper end of the rotating sleeve, and the motor shaft gear is meshed with the rotating sleeve gear for transmission.

[0021] A transmission shaft 7 is installed in the rotating sleeve to guide and move in the up-down direction. The transmission shaft 7 and the rotating sleeve 6 are locked by a spline bar extending in the up-down direction. The transmission shaft can move up and down in the inner hole of the rotating sleeve. When the transmission shaft is matched with the inner hole of the rotating sleeve, the transmission shaft cannot rotate relative to the rotating sleeve. The transmission shaft can also be pulled out from the lower side of the rotating sleeve.

[0022] The calibration unit also includes a lifting drum 12 connected to the upper end of the transmission shaft through a pull rope, and the lifting drum 12 is driven by a drum motor. Item 11 in the figure represents a reversing pulley for the pull rope to be wound around for reversing, and the reversing pulley 11 is located on the upper side of the rotating sleeve.

[0023] A calibration frame 8 is fixed to the bottom of the transmission shaft 7, and a standard weighing sensor 13 corresponding to the rolling of the running wheel is arranged on the calibration frame 8. When the lifting drum 12 lowers the transmission shaft, the transmission shaft 7 can be disengaged from the bottom of the rotating sleeve.

[0024] The transmission shaft is fixed to one end of the calibration frame. The upper end of the transmission shaft is provided with a tapered guide section 10 which is smaller at the top and larger at the bottom, and the pull rope 5 is connected to the top of the tapered guide section 10.

[0025] The calibration frame has a mounting hole which passes through the calibration frame in the up-down direction. The standard weighing sensor 13 is adapted to be arranged in the mounting hole. A sensor limit rod 21 is installed on the calibration frame to guide movement in the front-back direction. The standard weighing sensor is provided with a limit rod socket 23 which cooperates with the sensor limit rod. When the front end of the sensor limit rod 21 is not inserted into the limit rod socket 23, the standard weighing sensor can move up and down relative to the calibration frame; when the sensor limit rod 21 is inserted into the limit rod socket 23, the standard weighing sensor is fixed relative to the calibration frame. At this time, the bottom of the standard weighing sensor is arranged flush with the bottom of the calibration frame.

[0026] The calibration frame is provided with a limit rod reset spring 22 which applies a forward force to the sensor limit rod. A walking wheel pressing pedal 14 is hinged on the calibration frame at the rear side of the standard weighing sensor. The walking wheel pressing pedal 14 is a movable pedal that can rotate around the hinge axis. A walking wheel pressing pedal reset spring 16 is provided on the lower side of the walking wheel pressing pedal. The walking wheel pressing pedal is transmission-connected with the sensor limit rod. When the walking wheel pressing pedal is pressed from back to front by the corresponding walking wheel, the sensor limit rod moves backward and escapes from the limit rod socket; when the walking wheel pressing pedal is pressed from front to back by the corresponding walking wheel, the sensor limit rod moves forward so that the front end of the sensor limit rod is inserted into the limit rod socket.

[0027] Specifically, the walking wheel rolling pedal and the fiber rod are connected by a ratchet pawl transmission mechanism 17, the ratchet pawl transmission mechanism includes a ratchet 19 arranged coaxially with the walking wheel rolling pedal, the ratchet 19 can rotate relative to the walking wheel rolling pedal 14, the ratchet pawl transmission mechanism also includes a driving pawl 26 and a braking pawl 27 cooperating with the ratchet, the driving pawl 27 is arranged on the walking wheel rolling pedal 14, the ratchet pawl transmission mechanism also includes a transmission wheel 18 arranged coaxially with the ratchet, the transmission wheel 18 is sequentially provided with a transmission tooth segment 24 and an optical axis segment 25 along the circumferential direction, and there is no tooth on the optical axis segment 25. In this embodiment, there are two transmission tooth segments and two optical axis segments on the transmission wheel, and the rear end of the sensor limit rod is provided with a rack 20 for meshing with the transmission tooth segment 24. When the walking wheel rolling pedal is rolled once, the transmission wheel rotates to realize the switching of the transmission tooth segment, the optical axis segment and the rack. The cooperation of the driving pawl, the braking pawl and the ratchet belongs to the prior art.

[0028] A fixed pedal 15 is arranged at the front side of the running wheel rolling pedal, a brake pawl 27 is arranged on the fixed pedal, and a spring sheet 28 for applying pressure to the brake pawl is also arranged on the fixed pedal.

[0029] When using, Figure 1As shown, the frame first moves to the weighing platform of the instrument to be calibrated, and then the rotating sleeve rotates the transmission shaft and the calibration frame 90 degrees, and the standard weighing sensor on the calibration frame is adjusted to the front side of the corresponding running wheel, and then the calibration frame is lowered by pulling the rope until the calibration frame contacts the weighing platform. At this time, the upper end of the transmission shaft is released from the rotating sleeve, and the rope can be lowered to ensure that the calibration frame is fixed relative to the weighing platform when the frame moves forward. In actual use, if the posture of the calibration frame is slightly offset, the staff can manually adjust the posture of the calibration frame so that the fixed pedal and the running wheel crushing pedal are located in front of the corresponding running wheel. Then, the traveling wheel moves forward, and when the traveling wheel rolls over the traveling wheel rolling pedal, the traveling wheel rolling pedal drives the ratchet to rotate through the driving pawl, and the transmission wheel fixed with the ratchet also rotates, so that the transmission tooth segment on the transmission wheel engages with the rack, thereby driving the sensor limit rod to move backward, and the front end of the sensor limit rod is disengaged from the limit rod plug hole. At this time, the standard weighing sensor is in a free state, and when the traveling wheel passes through the traveling wheel rolling pedal, the traveling wheel rolling pedal is reset, and the ratchet is locked by the braking pawl. The traveling wheel travels to the standard weighing sensor in a free state, and the weight of the frame can be transmitted to the weighing platform through the traveling wheel and the standard weighing sensor, so that the weighing sensor of the scale can be calibrated through the standard weighing sensor.

[0030] After the calibration is completed, the frame moves backward. At this time, the walking wheel rolls over the walking wheel rolling pedal again. The walking wheel rolling pedal drives the ratchet to rotate, and the transmission wheel fixed with the ratchet also rotates, so that the optical axis section on the transmission wheel engages with the rack. At this time, under the action of the limit rod reset spring, the sensor limit rod moves forward, and the front end of the sensor limit rod is inserted into the limit rod jack of the standard weighing sensor. At this time, the standard weighing sensor is fixed to the calibration frame. When the walking wheel is completely driven out of the fixed pedal, the transmission shaft and the calibration frame can be retracted by pulling the rope.

[0031] The implementation of the calibration method of the present invention is as follows: Figures 1 to 8 As shown: In the first step, the frame of the scale calibration device is moved to the weighing table of the scale to be calibrated through the running wheels; in the second step, the rotating sleeve rotates with the transmission shaft and the calibration frame, so that the standard weighing sensor is located in front of the corresponding running wheel, and the transmission shaft is located on the left or right side of the corresponding running wheel; in the third step, the lifting drum lowers the calibration frame through the pull rope until the calibration frame falls on the weighing table; in the fourth step, the pull rope continues to be lowered, the frame moves forward, the calibration frame does not move relative to the weighing table, and each running wheel moves to the standard weighing sensor of the corresponding calibration unit respectively, and the weighing sensor of the scale to be calibrated is calibrated by the sum of the readings of each standard weighing sensor; in the fifth step, after the calibration is completed, the running wheel moves backward, the running wheel is removed from the corresponding standard weighing sensor, the rotating sleeve moves to the upper side of the corresponding transmission shaft, the lifting drum lifts the corresponding transmission shaft through the pull rope, and the transmission shaft returns to the corresponding rotating sleeve. The specific structure of the scale calibration device is the same as the scale calibration device described in the above embodiments, and will not be described in detail here.

[0032] In the above description of this specification, unless otherwise clearly specified and limited, the terms "fixed", "installed", "connected" or "connected" should be understood in a broad sense. For example, with regard to the term "connection", it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. Therefore, unless otherwise clearly defined in this specification, those skilled in the art can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0033] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "up", "down", "front", "back", "left", "right", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", "center", "longitudinal", "lateral", "clockwise" or "counterclockwise", etc., which indicate the orientation or position relationship, are based on the orientation or position relationship shown in the drawings of this specification, and are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or element involved must have the specific orientation, be constructed and operate in a specific orientation. Therefore, the above-mentioned orientation or position relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0034] In addition, the terms "first" or "second" used in this specification to refer to numbers or ordinals are only used for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this specification, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A weighing instrument calibration device, characterized in that: The invention comprises a frame provided with traveling wheels, and calibration units corresponding to the number of traveling wheels are arranged on the frame, and each calibration unit comprises a rotating sleeve whose rotating axis extends in the up-down direction and is located in front of the corresponding traveling wheel. The rotating sleeve is driven by a rotating sleeve driving mechanism, and a transmission shaft is installed in the rotating sleeve for guiding movement in the up-down direction, and the transmission shaft is engaged with the rotating sleeve for stopping rotation. The calibration unit also comprises a lifting drum connected to the upper end of the transmission shaft by a pull rope, and a calibration frame is fixed to the bottom of the transmission shaft, and a standard weighing sensor for the corresponding traveling wheel to crush is arranged on the calibration frame, and when the lifting drum lowers the transmission shaft, the transmission shaft can escape from the bottom of the rotating sleeve.

2. The weighing instrument calibration device according to claim 1, characterized in that: The transmission shaft is fixed to one end of the calibration frame.

3. The weighing instrument calibration device according to claim 1, characterized in that: The upper end of the transmission shaft is provided with a tapered guide section which is smaller at the top and larger at the bottom, and the pull rope is connected with the top of the tapered guide section.

4. The weighing instrument calibration device according to any one of claims 1 to 3, characterized in that: The calibration frame has an installation hole that penetrates the calibration frame in the up-down direction, and the standard weighing sensor is adapted to be arranged in the installation hole. A sensor limit rod is installed on the calibration frame for guiding movement in the front-back direction, and a limit rod socket that cooperates with the sensor limit rod is provided on the standard weighing sensor. A limit rod reset spring that applies a forward force to the sensor limit rod is provided on the calibration frame. A walking wheel crushing pedal is hinged on the rear side of the standard weighing sensor on the calibration frame, and a walking wheel reset spring is provided on the lower side of the walking wheel crushing pedal. The walking wheel crushing pedal is transmission-connected with the sensor limit rod. When the walking wheel crushing pedal is crushed from back to front by the corresponding walking wheel, the sensor limit rod moves backward and comes out of the limit rod socket; when the walking wheel crushing pedal is crushed from front to back by the corresponding walking wheel, the sensor limit rod moves forward so that the front end of the sensor limit rod is inserted into the limit rod socket.

5. The weighing instrument calibration device according to claim 4, characterized in that: The walking wheel rolling pedal and the fiber rod are connected through a ratchet pawl transmission mechanism, the ratchet pawl transmission mechanism includes a ratchet arranged coaxially with the walking wheel rolling pedal, the ratchet pawl transmission mechanism also includes a driving pawl and a braking pawl matched with the ratchet, the driving pawl is arranged on the walking wheel rolling pedal, the ratchet pawl transmission mechanism also includes a transmission wheel arranged coaxially with the ratchet, the transmission wheel is provided with transmission tooth segments and optical axis segments in sequence along the circumferential direction, the rear end of the sensor limit rod is provided with a rack for meshing with the transmission tooth segment, the walking wheel rolling pedal is rolled once, and the transmission wheel rotates to realize the switching of the transmission tooth segment, the optical axis segment and the rack.

6. The weighing instrument calibration device according to claim 5, characterized in that: A fixed pedal is arranged on the front side of the running wheel rolling pedal, and a brake pawl is arranged on the fixed pedal.

7. A calibration method using the weighing instrument calibration device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: a first step, a frame is moved to a weighing platform of a weighing instrument to be calibrated via running wheels; a second step, a rotating sleeve rotates with a transmission shaft and a calibration frame, so that a standard load cell is located at the front side of a corresponding running wheel, and the transmission shaft is located at the left or right side of the corresponding running wheel; a third step, a lifting drum lowers the calibration frame via a pull rope until the calibration frame falls on the weighing platform; a fourth step, the pull rope continues to be lowered, the frame moves forward, the calibration frame remains stationary relative to the weighing platform, each running wheel respectively moves to a standard load cell of a corresponding calibration unit, and the load cell of the weighing instrument to be calibrated is calibrated by the sum of the readings of each standard load cell; a fifth step, after the calibration is completed, the running wheels move backward, the running wheels are removed from the corresponding standard load cell, the rotating sleeve moves to the upper side of the corresponding transmission shaft, the lifting drum lifts the corresponding transmission shaft via the pull rope, and the transmission shaft returns to the corresponding rotating sleeve.

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