The factors influencing the synchronization of a HPHT Hydraulic Cubic Press are mainly divided into two major categories: hydraulic component factors and equipment mechanical factors.
Here is a detailed elaboration of each influencing factor:
I. Hydraulic Component Factors
1. Influence of the Overflow Valve
    The overflow valve is a crucial component in the hydraulic system for controlling system pressure.
    When subtle changes occur inside the overflow valve, the system exhibits various symptoms, such as previously adjusted synchronization quickly changing.
    During the return stroke of the system, if the pump pressure gauge pointer oscillates back and forth after reaching the set pressure, this often indicates unstable pressure within the overflow valve.
    This instability can be caused by damage to the O-ring within the valve sleeve, leading to internal leakage.
    Although internal leakage might not be noticeable at high pressures, the pressure instability it causes at low pressures will affect the adjustment of synchronization pressure between the cylinders, requiring timely repair to restore stable synchronization.
2. Influence of the Return Oil Check Valve
    The influence of the return oil check valve on press synchronization is quite distinctive.
    If, during the adjustment phase, a single cylinder advances while other cylinders also micro-advance, or if blocks appear during synthesis, this may indicate a negative effect from the return oil check valve.
    When the spring of the check valve used for return oil is too stiff, its opening pressure will be higher, creating greater back pressure.
    During piston advancement, due to excessive back pressure from the check valve, the piston's return oil path cannot flow normally, and the oil will flow back to other cylinders, pushing their pistons forward.
    This results in the active cylinder's piston advancing while the fixed cylinders' pistons also micro-advance during synthesis. This leads to inconsistent force application between active and fixed cylinders, disrupting synchronization.
    Therefore, the check valve used for return oil should have a softer spring, with an opening pressure of less than 0.04 MPa.
3. Influence of the Solenoid Directional Valve
    If, after checking the above situations, synchronization still varies, or if the piston rebounds after reaching its return position, or if the limit ring in the fixed cylinder is loose, then the solenoid directional valve corresponding to that working cylinder needs to be checked.
    When the solenoid directional valve spool is stuck or does not move fully, it can cause oil leakage between oil chambers, leading to loss of control over the piston.
    n such cases, the solenoid directional valve should be overhauled or replaced.
4. Influence of the Throttle Valve
    During the pre-synthesis debugging of a new press, it is common to encounter situations where adjusting a certain throttle valve has no effect on the flow rate and pressure of its corresponding working cylinder.
     After ruling out insufficient oil pump flow, it can often be found that the triangular groove on the valve spool, designed for oil flow, is too small, obstructing oil entry.
    The solution is to enlarge the triangular groove or replace the valve to enable the throttle valve to properly regulate flow.
5. Influence of the Two-Position Seven-Way Valve
    The influence of the two-position seven-way valve on synchronization is arguably the most subtle and most serious.
    At the moment of transition from filling to overpressure, if the pump pressure gauge pointer points to the set pressure of the overflow valve, it may be necessary to check the coaxiality of the two-position seven-way valve spool.
    When the valve spool exhibits taper, its movement is not complete, leading to reduced and inconsistent opening of the oil holes between the valve body and spool. This can cause uneven low-pressure force application across cylinders during filling. In this case, the spool's taper issue should be addressed.
    When the valve spool is normal, the pump pressure gauge should rise simultaneously with the high-pressure gauge at the moment of transition from filling to overpressure.
     If irregular and frequent cracking occurs during the synthesis process, the two-position seven-way valve spool should be removed, and the valve spool or valve body's oil holes should be carefully inspected for cracks.
    When cracks appear in the oil holes of the valve spool or valve body, the two-position seven-way valve will cross-leak oil under ultra-high pressure, leading to unbalanced pressure distribution across cylinders, destroying synchronization at high pressure, and consequently causing cracking. In this situation, the valve spool or valve body should be replaced.
    Because two-position seven-way valves are often of a sealed design and usually installed underground, pre-inspection is difficult. Among all hydraulic component failures that affect synchronization, the two-position seven-way valve is the most critical and requires sufficient attention.
II. Equipment Mechanical Factors
1. Influence of Stroke Adjustment
    The extent of stroke adjustment primarily reflects through the synthetic rod and is embodied in the solid block.
    When using a solid block to check synchronization, if the dimensions of corresponding faces are consistent but the sealing edges vary in thickness, this is typically due to improper stroke adjustment.
    In this case, the piston stroke should be readjusted, for example, by retracting fixed pistons or adjusting the stroke rod, to ensure consistent sealing edge thickness of the solid block.
2. Influence of Working Cylinder and Process Holes
    In working cylinders with flange support structures, return process holes are opened on the side of the working cylinder flange, typically sealed by welding.
    If the weld seam is too high, it will prevent the bottom of the flange from contacting the hinge beam support surface, effectively leaving the working cylinder suspended.
    During low-pressure synchronization adjustment of the press, this might not be evident, but at high pressure, the weld seam cannot withstand the load, and the working cylinder retracts, causing a sudden and drastic change in the previously adjusted synchronization. This can be observed from severe deformation of the synthetic rod.
    When encountering this situation, relevant dimensions between cylinders should be carefully checked, or the direction of the cylinder can be identified from the deformation of the synthetic rod, to process the weld seam and eliminate its adverse effects.
3. Influence of Working Cylinder Flange Support Bottom
    Similar to the above situation, if the bottom of the working cylinder flange support or the hinge beam support surface is unevenly machined, it can lead to plastic deformation of the cylinder body flange support bottom under ultra-high pressure, causing elastic changes in the cylinder body.
    This can also lead to synchronization changes between the cylinders.
    During maintenance, attention should be paid to checking and addressing these issues to avoid increasing top hammer consumption.
In summary, to improve the synchronization accuracy of a HPHT Hydraulic Cubic Press, it is crucial to identify and eliminate the aforementioned influencing factors and adopt correct adjustment methods to limit unfavorable factors within a controllable range.