What is the working principle of a gantry-type high-speed punch press?

The operating principle of the Longmen high-speed punch press is based on energy conversion and mechanical transmission. It achieves efficient, stable stamping operations through a precision transmission system and advanced control technology. Its core processes and key components are as follows:

I. Core Power Transmission Process

Motor Drive and Flywheel Energy Storage

The motor serves as the power source, driving the flywheel to rotate at high speed via a V‑belt or coupling. The flywheel is made of high‑density cast iron or alloy steel, and its primary function is to store kinetic energy, acting as an “energy reservoir” to ensure stable power delivery during stamping operations. For example, in continuous stamping processes, the flywheel can release its stored energy to compensate for any short‑term power deficits in the motor.

Precise control of the clutch and brake

Clutch: Under control system commands, the clutch engages to transmit power from the flywheel to the crankshaft, initiating the stamping cycle. Its response time is typically on the order of milliseconds, ensuring instantaneous power transmission.

Brake: After stamping is completed, the brake actuates rapidly to bring the slide to a stop at the designated position, ready for the next cycle. The brake is driven hydraulically or electromagnetically, ensuring a short braking distance and precise positioning.

Transmission and Conversion Between the Crankshaft and Connecting Rod

Crankshaft: Converts the rotational motion of the flywheel into the reciprocating motion of the connecting rod. The crankshaft is forged from high-strength alloy steel and precision ground to ensure radial runout of ≤0.005 mm, thereby minimizing vibration and noise.

Connecting rod: It is connected to the crankshaft via a ball joint or pin-type mechanism, converting rotary motion into the linear reciprocating motion of the slider. The design that matches the connecting‑rod length with the crankshaft’s eccentricity directly affects the slider’s stroke and velocity.

II. Slider Motion and Mold Coordination

Slider guide system

The slide block features an extended guide‑way design and is equipped with either a four‑guide‑post or an eight‑guide‑post configuration, with the clearance between the guide posts and guide bushings maintained within 0.002–0.005 mm. The guide posts are hard‑chrome plated, while the guide bushings are made of bronze alloy or steel liners, ensuring smooth motion and excellent resistance to eccentric loads. For example, the eight‑guide‑post arrangement, combining four circular guide posts with four circular slide‑block guide posts, can accommodate eccentric loads up to ±5 mm without compromising accuracy.

Mold Installation and Pressure Transmission

Upper die: Fixed to the bottom of the slide and connected to it via a die holder. The die holder is made of high‑strength cast iron and undergoes stress‑relief annealing to eliminate internal stresses, ensuring dimensional stability over long-term use.

Lower die: Mounted on the worktable and secured using T-slots or a quick‑positioning device. The worktable surface shall have a hardness of ≥HRC50 to resist die pressure and wear.

Stamping process: The slide drives the upper die downward, and in conjunction with the lower die, it applies pressure to the sheet metal, causing it to undergo plastic deformation or fracture and separation according to the die’s contour. Stamping forces can reach several thousand tons, depending on the machine type and die design.

III. Coordinated Operation of Auxiliary Systems

Lubrication system

An electronic timed automatic lubrication system is employed, using an oil pump to deliver lubricant to critical friction points such as guide posts, guide sleeves, the crankshaft, and connecting rods. Lubricant viscosity should be selected with consideration for its ability to form a stable oil film under high-speed operating conditions; for example, ISO VG 46 or VG 68 hydraulic oil may be used. The system is equipped with an oil-level sensor that triggers an automatic shutdown for protection in the event of insufficient lubricant.

Cooling system

For high-speed moving components such as crankshafts and connecting rods, forced cooling is employed to prevent overheating and the resulting loss of precision. Cooling methods include air cooling and water cooling; among these, water‑cooling systems are more efficient, as they remove heat by circulating a coolant. For example, a certain model of gantry‑type high‑speed punch press utilizes a closed-loop water‑cooling system that keeps the temperature of critical components at or below 60°C.

Feeding system

Equipped with a high-speed roller feeder or an NC servo feeder, the system achieves precise sheet‑metal positioning and continuous feeding. Feed pitch accuracy can reach ±0.01 mm, and feed speed is synchronized with slide motion, ensuring stable stamping cycles. For example, in motor stator and rotor stamping production, the feeding system must accommodate a stamping frequency of 800–1,000 strokes per minute.

IV. Control Technology for Automation

PLC and Touchscreen Control

A PLC (Programmable Logic Controller) is used as the core control unit, with stamping parameters—such as stroke, speed, and number of strokes—set via a touch screen. The PLC continuously monitors equipment status, including clutch/brake conditions and lubricant pressure, and triggers alarms or initiates an emergency stop in case of abnormalities.

Servo motor drive (optional)

Some high-end models employ servo motors to directly drive the crankshaft, enabling precise control of the slide’s motion. The servo motor uses an encoder to provide position feedback, allowing adjustment of the stamping velocity profile—such as acceleration, deceleration, and dwell phases—to meet the specific requirements of different materials. For instance, in the stamping of precision electronic components, servo‑driven systems can minimize material springback and enhance product consistency.