How to cool down a fixed table press

As the core equipment in the field of metal stamping, fixed table punching machines are widely used in mass production processes such as punching, cutting, bending, and forming due to their stable structure, high rigidity, and stable processing accuracy. However, during continuous and high-intensity operations, the heat generated by mechanical friction and plastic deformation will continue to accumulate, leading to an increase in equipment temperature. Excessive temperature not only affects machining accuracy and product quality, but also exacerbates component wear, shortens equipment life, and even causes malfunctions and shutdowns. Therefore, implementing effective cooling and temperature reduction for fixed table presses is a key step in ensuring their efficient, stable, and long-lasting operation. This article will systematically explain the heat source, cooling principle, and various cooling methods of fixed table punching machines.

1. Analysis of heat source: knowing its nature, knowing its reasons

To effectively cool down a fixed table press, it is first necessary to accurately locate where its heat comes from. The main heat sources can be attributed to the following three aspects:

1. Core frictional heat: spindle and bearing, slider and guide rail

-Main shaft/crankshaft bearing system: This is the primary mechanical friction heat source. When the crankshaft or eccentric gear of a fixed table press rotates at high speed, continuous friction is generated inside its supporting bearings (such as rolling bearings or sliding bearings). If the lubrication is insufficient or improper, the friction coefficient will rise sharply, generating a large amount of heat in a short period of time, causing the bearing temperature to rise too high, resulting in erosion or locking, which is one of the most serious mechanical failures.

-Sliding block and guide rail pair: The high-speed reciprocating motion of the sliding block on the guide rail is another key friction point. Although modern punching machines often use linear guides or self-lubricating pads, the friction between contact surfaces is still considerable under high-frequency and high load conditions. Heat accumulation can cause thermal deformation of the guide rail, directly affecting the operating accuracy of the slider, and thus affecting the alignment of the upper and lower molds, resulting in product size deviation and abnormal mold wear.

2. Heat during the working process: plastic deformation energy of materials

At the moment of stamping, the mold exerts tremendous pressure on the metal sheet, causing it to undergo plastic deformation (such as shearing, bending, and stretching). The vast majority (about 90%) of mechanical work is converted into heat energy, which mainly accumulates on the processed materials and molds. Although a portion of the heat will be carried away with the workpiece, a considerable amount will still be conducted to the mold and mold base, and ultimately dissipated through the equipment bed. During continuous production, the mold temperature can rise to a very high level, which may not only change the processing performance of the material, but also accelerate the wear and thermal fatigue of the mold itself.

3. Auxiliary system heat: motor and brake

-Main motor: The main motor that drives the flywheel and crankshaft of the punch press itself has energy loss during operation, which is dissipated in the form of thermal energy.

-Clutch and brake: Especially on the punch press of wet clutch/brake, the sliding friction when the friction plate is engaged and disengaged will generate heat, causing the temperature of the lubricating oil to rise. If the cooling is poor, it will lead to a decrease in oil performance, ineffective braking, and delayed response.

2. The core method of cooling and temperature reduction: from foundation to system

Regarding the above-mentioned heat sources, the cooling and temperature reduction of fixed table presses is a systematic project, mainly focusing on two core aspects: "lubrication cooling" and "external forced heat dissipation".

（1） Cooling of the core lubrication system: a fundamental solution

Lubrication is not only a means of reducing friction and wear, but also an important medium for removing heat. Therefore, cooling the lubrication system itself is crucial.

1. Oil cooler of thin oil circulation lubrication system:

For fixed table punch presses that use forced circulation lubrication, the lubrication station is the key to cooling. Integrating an oil cooler into the lubrication system is a standard configuration. Its working principle is:
-Air cooled oil cooler: By using a fan to forcefully blow air, it flows through a cooling coil with fins, and the heat of the high-temperature lubricating oil inside the tube is carried away by the air. This method has a simple structure, easy maintenance, and does not require a water source, making it the preferred choice for most small and medium-sized fixed table presses. The cooling efficiency depends on the area of the heat dissipation fins and the air volume of the fan.

-Water cooled oil cooler: Through internal coils, cooling water flows outside the pipes, and high-temperature lubricating oil flows inside the pipes, exchanging heat through the metal pipe walls. The cooling efficiency of water cooling is much higher than that of air cooling, and it is suitable for large, high-speed, continuous operation fixed table presses, or in workshops with high ambient temperatures. But it requires a stable cooling water source and a matching pipeline system.

2. Oil cooling for wet clutch/brake:

For punch presses equipped with wet clutch brakes, the cooling of their working oil (which also serves as a lubricant and transmission medium) is more critical. Usually equipped with independent or integrated cooling devices in the main lubrication system, the principle is the same as above. Maintaining the clutch oil temperature within a reasonable range (usually below 60 ° C) is a prerequisite for ensuring its rapid response and long service life.

（2） External forced air cooling and air convection

1. Main motor cooling fan: The main motor of the punching machine usually comes with a cooling fan, which forcibly cools the stator and rotor of the motor through an internal air duct to prevent the motor from burning out due to overheating. Ensure that the motor ventilation opening is unobstructed.
2. Electrical cabinet air conditioning/heat exchanger: Modern fixed table punching machines use numerical control systems (CNC) and servo drives, and electronic components such as frequency converters, servo drives, PLCs, etc. inside the electrical cabinet are important heating elements. To ensure its stable operation, electrical cabinets are usually equipped with:
-Cabinet air conditioning: It can actively cool and maintain the temperature inside the cabinet below the ambient temperature, with the best effect, but it consumes more energy.
-Heat exchanger: The heat inside the cabinet is transferred to the outside of the cabinet through internal circulation fluid, and is dissipated by an external fan. Efficiency is between air conditioning and fans.
-Ventilation fan: The simplest way is to draw in external cold air through a filter and expel hot air. Suitable for occasions with low heat generation and relatively clean environment.

3. Natural heat dissipation and auxiliary ventilation of the body: By optimizing the rib plate structure design of the fixed table press, the effective heat dissipation area is increased to promote natural convection. On machine tools with high temperature environments or high heat loads, industrial fans can be installed at key heating areas (such as near bearing seats) for targeted forced air blowing to enhance heat dissipation.

（3） Cooling of mold and working area

1. Cooling channel inside the mold: For high-speed stamping or warm forming processes, a cooling water channel can be designed inside the mold, and circulating cooling water can be injected into the channel through a mold warming machine or chiller to directly remove the heat accumulated in the mold. This is the most effective method to control mold temperature, ensure product accuracy and surface quality.

2. Compressed air blowing: At the feeding or discharging station, dry compressed air is used to blow onto the surface of the mold or workpiece, which can not only remove waste and debris, but also have a certain air cooling effect.

3. System optimization and maintenance management

Even the best cooling system requires proper use and maintenance.
1. Correct selection and regular replacement of lubricating oil: Choosing lubricating oil with appropriate viscosity, good oxidation resistance, and thermal stability is the foundation. Lubricating oil that works at high temperatures for a long time will oxidize and deteriorate, forming sludge, blocking oil circuits and coolers, and causing a sharp decrease in its heat dissipation capacity. The lubricating oil and filter element must be replaced strictly according to the maintenance cycle.
2. Regular cleaning of cooling devices:
-Air cooler: The heat dissipation fins are easily clogged by dust and cotton wool, and must be cleaned regularly with compressed air or high-pressure water guns to ensure smooth ventilation.
-Water cooler: To prevent the formation of scale, chemical cleaning can be carried out regularly according to the water quality, or softened water can be used as the cooling medium.
-Environmental temperature control: The overall ventilation and cooling of the workshop are the foundation. By installing rooftop fans, industrial large fans, and even overall workshop air conditioning, the ambient temperature can be reduced, creating a more favorable working condition for all cooling systems (especially air coolers) and achieving twice the result with half the effort.

-Operation monitoring and warning: Install temperature sensors in key areas such as spindle bearings and lubricating oil tanks to monitor temperature changes in real time. Once the temperature exceeds the set threshold, an alarm or shutdown will be immediately triggered to prevent the equipment from operating in an overheated state and achieve predictive maintenance.

Cooling down a fixed table press is not a single solution, but a comprehensive project from internal lubrication to external heat dissipation, from core components to auxiliary systems, from hardware configuration to maintenance management. The core idea is to reduce frictional heat generation through an efficient lubrication system and use circulating cooling media (oil, water, air) to quickly dissipate and dissipate the generated heat. A well-designed and well maintained cooling system is a solid guarantee to ensure the high rigidity and precision advantages of fixed table presses, and to achieve safe, efficient, long-term, and low-cost operation.