As we all know, the final precision of sheet metal bending products depends on the optimal combination of bending equipment, bending tooling systems (including dies, clamps, and compensators), bending materials, and bending operators. The bending machine tooling system consists of bending dies, clamping systems, and compensating systems. The importance of bending dies and compensating systems in bending accuracy is undeniable, but many industry professionals have limited knowledge about the clamping system. In this article, we will discuss the clamping system used in bending and how it can free up manual labor and improve bending precision and efficiency.
Before sheet metal bending, the workpiece may have undergone multiple value-added production processes such as stamping, cutting, and deburring. This requires the bending process to ensure strict accuracy and consistency to reduce the generation of expensive scrap and lower costs. We all know that good bending equipment must meet these requirements, but the importance of a good clamping system is often overlooked. A good clamping system not only saves time but also ensures accuracy and reduces the number of test bends. So, what are the different clamping systems? Let's provide an overview of the advantages and disadvantages of different clamping systems.
Two Types of Clamping Systems
Bending machine tooling systems have two types of clamping systems: manual clamping and automatic clamping. Each clamping system has different versions available in the market.
Manual Clamping System
The manual clamping system is an effective and economical clamping method for bending machines that do not require frequent die changes. Manual clamping involves manually tightening each clamp plate, which is the most basic and time-consuming clamping method. When individual clamp plates are manually tightened, they do not automatically form a continuous clamping line. The clamping force of each section of the die is uneven, and the die cannot immediately align, requiring time-consuming adjustments and relying on experienced operators. To overcome the reliance on manual labor, eliminate the need for adjustments, and improve precision, a manual clamping system with clamping pin structures can provide consistent clamping force along the entire working length, eliminating the need for further adjustments after each section of the die is clamped. The manual clamping system with clamping pin structures features automatic seating and automatic calibration mechanisms, ensuring precise alignment and seating of the dies.
Automatic Clamping System
The automatic clamping system is suitable for bending machine tooling that requires frequent and rapid die changes. Based on the concept of "single-point operation," the automatic clamping system allows the clamping and loosening of dies to be achieved with the press of a button, eliminating the tedious experience of manual clamping. The power source for the automatic clamping system can be electric, hydraulic, or pneumatic. The most basic automatic clamping system consists of segmented independent clamp plates and power cylinders driven by the aforementioned power sources. Although this clamping system eliminates the time-consuming manual clamping method, the issue of die positioning accuracy still exists because the clamp plates are still segmented and independent. How can we avoid activating individual clamp plates separately for clamping the dies? This accuracy issue can be addressed by using a medium to drive a mechanism that clamps the dies throughout the entire length of the bending machine. The automatic clamping system belongs to a full-length clamping method, with hydraulic or pneumatic power sources.
The automatic clamping system can be divided into hydraulic clamps and pneumatic clamps. For hydraulic clamps, they are equipped with hydraulic oil pipes that are the same length as the bending machine. When hydraulic oil is supplied at a certain pressure, the hydraulic oil pipes expand, pushing the hardened clamping pins to clamp the dies. The hydraulic power system must remain open to ensure the clamping function (power-locked clamps). For pneumatic clamps, air pressure replaces hydraulic pressure, allowing for faster clamping and loosening of the dies. The pneumatic clamping system uses compressed air to achieve the clamping function, and the air pressure acts on a self-locking wedge mechanism to provide a closed clamping function. Therefore, the clamping is fast and securely locked (closed clamps).
Manual clamping systems are more suitable for applications where die changes are infrequent. In such applications, we recommend using a manual clamping system. The hardened clamping mechanism ensures precise positioning, alignment, and clamping of each segmented die, thus ensuring bending accuracy.
If frequent die changes are required, we recommend an automatic clamping system, which has the following characteristics:
1. High efficiency: If there are multiple die changes in each shift, automatic die changing can improve bending efficiency and increase profitability.
2. Ergonomics: The operation is safe, ensuring the avoidance of work-related injuries.
3. Labor-saving: The system is easy to use, reducing the skill requirements for bending operators and reducing the company's dependence on skilled workers.
If sustainability is a priority, we recommend using pneumatic automatic clamping systems. Pneumatic clamping with self-locking functionality does not require continuous operation to maintain clamping, helping to reduce the use of hydraulic oil and lower energy consumption.
Compensation Equipment Tolerance
When the compensation accuracy of a bending machine decreases, how can the deformation of the product be avoided and achieve perfect bending accuracy through the configuration of the fixture system? As customer demands for the quality and details of sheet metal products continue to increase, automation and process optimization become more and more important. Automation and process optimization will have a significant impact on bending operators, as they will change the traditional way of using bending machines and tooling. Achieving perfect bending results cannot solely rely on experienced bending operators. The bending equipment and tooling system must also be stable to avoid deformation of the final product. How can this goal be achieved?
Deformation of the product caused by compensation accuracy decrease
The deformation of the final product is caused by tolerances in the horizontal direction (Tx) and vertical direction (Ty) during the bending process. Deviation in the horizontal direction is caused by inaccurate centerline positioning, which affects the accuracy of the side lengths of the sheet metal bending product. Tolerances in the vertical direction are caused by non-parallel upper and lower dies, which affect the accuracy of the product's angles. Excessive deviation in the Tx or Ty direction can lead to rework or rejection of the workpiece as non-conforming.
The upper and lower fixtures can easily compensate for local tolerances and achieve precise bending. However, mechanical compensation (deformation caused by overall compensation of the bending machine's hydraulic cylinder sinking) and tooling can achieve excellent bending results and achieve the best bending accuracy for the product.
