As manufacturing continues to advance, CNC turret punching plays a key role in flexible sheet metal processing, especially in the realm of custom commercial sheet metal manufacturing.
To maximize the potential of CNC sheet metal processing in production and increase punch press efficiency, commercial sheet metal shops have integrated the use of combined CNC punching and shearing machines.
This sophisticated equipment combines computer control technology, microelectronics, remote monitoring and precision manufacturing.
The combined CNC punching and shearing machine has automated loading and unloading systems, automatic sorting and stacking mechanisms, an automated storage system, and integrates modern management methods to realize a fully automated CNC punching and shearing process for sheet metal.
1. Processing unit: Combined punching and shearing machine
Introduction to CNC combined punching and shearing machine:
The combined CNC punching and shearing machine mainly consists of a CNC turret punch and a CNC right-angle shear, as illustrated in Figure 1.
The CNC turret punch is equipped with a rotating disc tool library, enabling punching, edge cutting and bending operations on sheet metal parts. CNC right angle shears are equipped with blades on the X and Y axis, designed to separate the sheet metal after it has undergone several operations.
For fully automated processing, parts must be within the equipment's working parameters. Therefore, establishing these parameters is crucial.
The combined punching and shearing machine has a punching force of 30 tons and a shearing force of 20 tons. Its tower houses 55 tool stations, including 21 A stations (mainly for small generic feature tools that do not require frequent changes), 24 B stations, 2 special rotary stations (mainly for medium generic feature tools, with a larger punch stroke to increase efficiency and rotation to adjust angles of rectangles, polygons, etc.), 4 C stations, 2 D stations and 2 E stations (normally for large generic cutting, shuttering, bending hole, embossing and other special operations ). Each feature tool has a unique code, for example, RO for round holes, RE for rectangles, DJ for polygons, and SQ for squares.
The maximum processing range of the machine is: X axis 3000mm, Y axis 1500mm, with a maximum sheet thickness of 6.35mm. The right angle shear can process up to 4mm thickness (for Q235 steel plates), with a punch processing accuracy of ±0.10mm.
Applications of CNC combined punching and shearing machine:
The two blades of the right-angle CNC scissors are perpendicular, with the X-axis blade capable of continuous cutting, eliminating the need for manual pre-cutting of the raw material. This increases efficiency in material layout and reduces waste. The layout of the two blades, as shown in Figure 2, indicates that the X-axis blade is longer than the Y-axis blade, arranged at a 90° angle.
The machine offers two cutting modes: full cut and half cut. In full cutting mode, the X and Y axis blades move simultaneously, producing well-defined right-angled parts.
In half-cut mode, the Y-axis blade remains stationary while the X-axis blade operates independently, mainly used when larger parts have specific features that can interfere with the Y-axis.
The choice between these modes is determined programmatically based on the actual situation.
After cutting, the waste and finished parts are transported via an automated bristle conveyor. Scraps of different sizes are automatically sorted into two separate bins during transmission.
At the same time, small residues from the tooling process are transported by another transport system, ensuring continuous and stable operation of the punching machine, eliminating equipment downtime. This process maximizes external transitions, significantly increasing the processing efficiency of sheet metal parts.
When the CNC punching and shearing combined machine processes varying thicknesses of metal sheets, the CNC turret punching tool library switches punching tools or forming tools based on technical standards.
CNC right angle shear adjusts blade gaps through electronic control, ensuring the quality of sheet metal cutting surfaces.
The importance of integrating CNC punching and shearing:
The right-angle cutting function provides critical support for automatic nesting processes, allowing parts to be automatically sorted and stacked. This function is essential to achieve full automation of the processing unit.
In contrast, traditional CNC punching requires manual intervention. Operators must pre-cut sheet metal using cutting machines based on part shape and size requirements before proceeding to the CNC programming phase.
Main benefits of CNC punch-shear combined machines for nesting processing:
1) The nesting layout is managed by automated nesting programming software, which also separates the parts from the waste, maximizing the use of raw materials.
2) The integrated nature of the machine eliminates the need for manual material transportation, increasing the precision of sheet metal processing. This not only reduces handling and waiting time, but also increases machine efficiency.
Processing unit automation functions
Composition of the Processing Unit:
The fully automated CNC punching and cutting unit is composed of automated hardware components and an informative control system, as illustrated in Figure 3.
The hardware components include: an automated raw material anchoring cart, raw material loading device, CNC punching-shearing combined machine, automatic waste ejection device, automatic spray coding device, automatic sorting mechanism and parts stacking, automatic parts anchoring cart and eight modules for photoelectric protection.
The informative control system encompasses the punch press control system (with CNC punching and right-angle cutting control systems), an interactive module for the MES+WCS+ punch control system and a photoelectric protection control module.
These eight core hardware modules underpin the entire automated processing journey.
On the other hand, the interactive module between MES+WCS and the punch control system is crucial for the unit's information management.
The processing unit uses the MES system for automated production scheduling. Scheduling software automatically extracts order details and nests them according to order specifications.
This ensures that parts, once automatically grouped and programmed, are manufactured from standard-sized raw materials. These standard raw materials are critical for automated storage.
After use, the materials are fully utilized, avoiding waste. The right-angle cutting function makes it easier to separate grouped parts.
Automatic material loading function:
The automatic material loading feature forms the basis for seamless integration between the processing unit and the automated storage system.
When the MES system dispatches order tasks to the punching unit, it simultaneously synchronizes the required standard raw material information with the intelligent storage dispatch center.
The shipping center then matches the raw material pallets in stock with the retrieval task sequence and automatically issues retrieval commands. As long as the machine tool is operational, the corresponding raw material pallet is transported to the machine's material inlet.
From here, the automated loading cart retrieves the raw material pallet and moves it to the automatic loading position. To accommodate different sheet metal loading requirements, the loading suction cup system is segmented to avoid empty suction, as illustrated in Figure 4.
A sheet separation device, installed on the loading robot arm, first lifts one corner of the sheet. The mechanism then lifts and vibrates the sheet to separate it, simulating manual separation.
After the material is clamped, its thickness is automatically measured to ensure consistency with order requirements. If the detected material thickness exceeds the standard sheet thickness, an alarm will be triggered, stopping the machine.
If the thickness is within the specified parameters, the machine continues operation. Finally, the raw material is transferred through the loading suction cups to the machine's positioning clamp for alignment.
At this stage, the processing unit completes the entire automated material loading process.
Automatic sorting and stacking function:
Right-angle part separation sets the stage for automatic sorting and stacking.
Once separated, these parts are semi-finished products. The stacking device categorizes and stacks these semi-finished items. The automatic stacking mechanism requires sheet sizes to be between a minimum of 400mm x 100mm and a maximum of 3000mm x 1500mm.
The sheet thickness must be between a minimum of 0.5mm and a maximum of 4mm (for carbon steel sheets), with a maximum stacking weight of 3,000kg.
The CNC programming of the processing unit uses automatic nesting programming software. After generating the processing program, the sorting program module identifies the parts within the program.
Parts with the same code are allocated to the same area of the semi-finished product tray, as shown in Figure 5.
Each area has a maximum stacking height of 500mm. If this height is exceeded, parts will be relocated to a different stacking area to avoid excessive stacking issues due to excessive amounts of identically coded parts.
After sending the processing program, the system reconfirms the actual placement of the parts in the stacking area. The photoelectric detection system also checks the stacking height of the parts.
If parts from the semi-finished product stacking area are urgently removed for the next operation, the operator must reset the corresponding code in the stacking area.
This allows the system to reintegrate it as available space, avoiding wasted stacking space.
After the stacking area is checked to meet part stacking requirements, the sorting device separates parts with the same code for sequential stacking. The sorting uses an automatic split roll style sorting and stacking mechanism, automatically transferring the cut pieces to the pallet of semi-finished product. The pallet is placed on a specialized transfer cart.
At the end of order processing, the cart receives an instruction to return the semi-finished products to storage. It then transports the pallet to the corresponding entry point of the automated storage system.
The storage system shuttle automatically stores the pallet of semi-finished product, with the MES system simultaneously creating return-to-storage information for the pallet.
For retrieval, simply search for the corresponding order number to locate the order position in the storage system and the pallet code, thus creating an automatic retrieval task and facilitating the retrieval of semi-finished parts.
Full Automation of the Processing Unit
MES Automated Scheduling and Dispatch
Production orders from the processing unit are automatically dispatched by the MES system based on scheduling logic. Order information includes essential production data such as material type, quantity, size specifications, coding, graphic details, program data, process flow information, and processing time.
Scholars discussed the production scheduling system that harmonizes SOA with flexible manufacturing techniques. They specifically analyzed planning and scheduling challenges in the production process and explained the methods and implementations of assigning tasks to machine stations, offering solutions to dispatch problems in the processing unit.
The production tasks of the fully automatic CNC punching unit adopt primary and backup system. The MES system assigns two orders to the same machine: the main order is the one in production and the next one as a backup. Once the primary order is complete, the backup will automatically become the primary.
As illustrated in Figure 6, the MES and WCS interaction module simultaneously programs the storage system to issue raw material retrieval tasks and material return tasks from the previous order.
Before processing begins, preparations are made by overlapping order operations, reducing internal changeover times, minimizing machine downtime, increasing equipment operating rates and achieving efficient production.
Fully Automated Processing Unit Production
Upon receiving the production task dispatched by the MES system, operators only need to check the tooling requirements of the processing program, ensure a safe production environment, and then start production of the order.
At this point, the equipment processes according to the NC code. If the order involves parts with special processes, the system will request tool changes when starting production of the order and operators will manually replace or supplement the corresponding tools.
When the MES system receives feedback about the start of order processing, it simultaneously dispatches the raw material retrieval task of said order to the warehouse system's WCS scheduling system.
The storage system cart then transports the corresponding raw material pallet to the anchoring position of the processing unit's material receiving cart.
When the processing unit receives information about the arrival of raw materials, the system programs the receiving cart to remove the materials. The subsequent processing operation does not require manual intervention.
After processing, automatic sorting of parts, stacking and transportation of waste are carried out. The sorting and stacking system categorizes parts by type and sequentially completes sorting and stacking tasks.
The system records all processing unit status information based on order cycles through order completion, and automatic reporting occurs throughout the process. The information management panel is illustrated in Figure 7.
After the order is completed, the semi-finished parts automatically connect to the warehousing system transport for storage, and the warehousing information is synchronized with the MES system.
Additionally, the processing unit is equipped with a networked multifunctional PC. Operators can log in to the MES system interface through this PC.
On the order report page, by clicking the graphic number, they can directly access the company's internal key document system, linking to the processing requirements and design drawings of corresponding parts, greatly facilitating on-site operations.
Conclusion
With the continuous development of the manufacturing industry, the widespread application of fully automated processing units that integrate automation and information technology will become increasingly prevalent.
This article describes a fully automatic CNC punching unit, mainly focusing on CNC punching and cutting machines, taking advantage of informative process management.
It maximizes the advantages of automated equipment and, to a certain extent, realizes a labor-reduced sheet metal production model, offering significant insights for industries such as sheet metal processing to achieve full automation.
