1.Product Photos
LR-SL600kN Class 0.1 Compressive Force Standard Machine (Stacking Type)
2.Product Application Scope
The LR-SL600 microcomputer-controlled stack-type force standard machine (compression mode) is designed for the metrological verification and testing of standard force-measuring instruments, weighing load cells, and force sensors. It fully complies with the requirements of JJG1116-2015 *Stack-type Force Standard Machine*, JJG669-2003 *Verification Regulation for Weighing Load Cells*, and JJG144-2007 *Verification Regulation for Standard Force-measuring Instruments*.
This machine is suitable for use by force value transfer institutions—such as metrology institutes and those specializing in aviation, aerospace, and national defense metrology—as well as by sensor manufacturing enterprises.
4.Product Design Features:
Special structural designs were implemented to meet the specific requirements regarding the calculation formulas for force value errors (loading and unloading cycles) and orientation errors in stacked-type force standard machines.
4.1. First Special Design: Force application point at the very top of the machine
Top-mounted plunger cylinder and top-mounted load cell. The dead weight of the reaction frame rests on the load cell. This ensures that the force application axis of the standard machine remains permanently coaxial with the gravity axis.
4.2. Second Special Design: Zero-clearance reaction frame
Piston movement adjusts the tension/compression space without altering the force reference datum.
Designs using rotating lead screws and nuts to adjust the tension/compression space are known as "clearance-type" reaction frames. For screw assemblies with diameters exceeding 100 mm, axial and radial clearances are typically no less than 1 mm, and ensuring consistency in clearance across two (or four) screw assemblies is difficult.
When the reaction frame is unloaded, gravity causes the screw assembly clearance to exist at the upper face of the lead screw threads.
When the reaction frame is loaded, the first step involves overcoming the dead weight of the upper crossbeam; at this point, the load cell registers a force equal to the weight of the upper crossbeam. The second step involves taking up the clearance in the screw assembly; during this phase, the load cell reading does not increase. In the third step, once the clearance is fully eliminated, the load cell begins to register continuous force; at this stage, the clearance shifts to the lower face of the lead screw threads.
The levelness of the upper and lower compression platens is calibrated in the unloaded state, where the load-bearing contact is at the upper face of the lead screw threads—meaning the levelness reference is the upper thread face. However, when the system reaches the third step and the load cell registers continuous force, the load-bearing contact shifts to the lower face of the lead screw threads—meaning the levelness reference effectively shifts to the lower thread face.
This shift in the levelness reference—compounded by errors in thread pitch and screw assembly clearance—invalidates the levelness calibration previously established. ...resulting in significant errors in force values and orientation.
A rigid reaction frame is known as a zero-clearance reaction frame; for a stacked-type force standard machine, this design eliminates structural flaws.
4.3. Third special design feature: Square reaction frame
The base and crossbeam utilize an integrated square structure, eliminating inconsistencies in deformation between the 0°/180° axes and the 90°/270° axes.
The rectangular beam structure found in some stacked-type force standard machine reaction frames is a serious design flaw.
Because the length and width of a rectangular beam differ, the force arms vary when the frame is under load, resulting in differing bending moments. According to bending stress theory (pioneered by Galileo), this leads to unequal deflection—meaning deformation along the length differs from that along the width—which causes the sensor to experience uneven loading across the two axes.
In a spatial force system defined by X, Y, and Z axes, the X and Y axes are horizontal and mutually perpendicular, while the Z axis represents the vertical line of force application. A reaction frame loaded at two points experiences forces symmetrical about point O along the X-axis, with no force applied along the Y-axis. This constitutes a classic simply supported beam model. The deformation of a simply supported beam resembles a crescent shape along the X-axis, whereas deformation along the Y-axis is significantly smaller. For a stacked-type force standard machine, the deformation values at the 0°/180° positions differ from those at the 90°/270° positions. This discrepancy significantly impacts the machine's force value accuracy and orientation error.
4.4. Fourth special design feature: Single-sensor force measurement
Using a single high-precision load cell for measurement avoids the synchronization issues associated with parallel-connected sensors.
What are the pros and cons of using a single sensor versus three sensors in parallel?
The advantage of single-sensor measurement lies in superior technical specifications regarding force value accuracy, repeatability, and orientation error; the disadvantage is the relatively higher cost. The advantages of using three sensors in parallel for force measurement are relatively low cost; the disadvantage is that, due to issues with force synchronization among the three sensors, the technical specifications are relatively less impressive.
Your message must be between 20-3,000 characters!
English
