Components of a Wire Mesh Welding Machine

You may wonder what factors determine a mesh welding machine’s speed and production capacity. In this article, we will thoroughly explain the components of a mesh welding machine and analyze the mesh production process.

Mesh welding machines on the market are categorized into two main types: 1. Semi-automatic 2. Fully automatic.

Wire feeding section

One significant difference between semi-automatic and fully automatic mesh welding machines is how the line wires are fed.

• In the semi-automatic mesh welding machine, the line wires are straightened to the desired length by a straightening machine, placed in bundles of, for example, 1000 pieces at the beginning of the machine’s input table, and fed into the mesh welding machine by the operator. This production method requires less space and the mesh produced with this method has a suitable flatness. It also does not require a guillotine machine to cut the mesh. However, to produce mesh with this method, a straightening machine for line wires is needed.
• In a fully automatic mesh welding machine, the line wires are unwound from coils placed on the spools. A pulley should be considered for each length of wire, which is placed on the chassis. After passing through the straightening roller and the wire storage part, the wires are fed to the mesh welding machine. In this method, you no longer need an operator to insert the wires, so the time spent inserting the wires in this process is eliminated. But this method has disadvantages, including
• Spending more money on setting up a production line
• It requires more space than a semi-automatic machine
• A guillotine machine is needed to cut the mesh to the desired dimensions
• It takes more time to change the line.

E- The storage volume of raw materials is larger

In both of the above methods, the cross wires are previously straightened into the desired dimensions by a straightening machine and are placed in the cross wire tank by an operator or an overhead crane, which is then fed to the machine by a wire feeder in the next step.

Wire Feeder

The period during which cross wires are welded, while the electrodes are going up, and the machine awaits the next cross wire, is referred to as the wire feeding time. Shortening this time is one of the most important timing items in the entire production.

The wire feeding time is crucial; if we can reduce this time from 1 second to 0.5 seconds, we can save a significant amount of time in mass production. For instance, in a 6-meter-long mesh sheet with 10-centimeter openings, there are 60 rows of welding points that need to be created. If the feeding time is cut in half, the total time saved would be 30 seconds (0.5 seconds multiplied by 60 rows). This reduction adds up to a considerable efficiency improvement.

The flatter these wires are, the smoother they will be during feeding. In addition, if the cross wire storage tank is closer to the electrodes, it is effective in reducing wire feeding time.

Types of wire feeders

Depending on the type of wire and the manufacturer, the wire feeder operates differently. Here, we describe two manufacturing methods we have previously experienced.

• In the most common method, cross wires—typically 2 meters long—are first straightened and cut by a straightening machine. After this process, they are placed into large bundles by either human labor or an overhead crane and then stored in a wire storage tank.

They are guided in an orderly line toward the electrodes and held in a precise position between the upper and lower electrodes by the magnet’s force.

B- In some machines, there is no wire feeder system. Instead, a spool of wire is placed on the side of the machine. During production, the wire is straightened and positioned appropriately on the welding electrodes simultaneously. The design, construction, and adjustment of this machine require high precision, as every hundredth of a second in delay affects the entire production process.

Pressure system of electrodes

First, it should be noted that the number and high speed of moving the electrodes and applying continuous pressure to the wires are of particular importance. To achieve the desired welding result, before starting the transformers, it is necessary to ensure a consistent and proportional pressure relative to the diameter and material of the wire. This can determine how the electrode pressure system works.

The essential aspect of achieving a quality weld is that, in addition to having the proper conditions for the wire and electrode, approximately 9 kilograms of force are needed per square millimeter. If the wire diameter is 6 mm, a continuous force of 250 kg is required to achieve the desired welding quality and minimize sparking. This value is obtained through experimentation.

Methods of applying pressure on electrodes

• Mechanical system: In this method, the lower electrodes are fixed while the upper electrodes move through a crank and sliding mechanism. The following are the advantages of this method:
• Very smooth and uniform movement due to top and bottom dead center
• movement with very high reliability
• No breakdowns and easy maintenance
• No errors during operation
• Possibility of use at high speeds
• This mechanism is not affected by atmospheric conditions like low temperatures or high humidity.

The drawbacks of this method include long manufacturing times, increased machining and preparation costs, and potential impacts when passing through the crank system’s bottom dead center. In addition, in this mechanism, all electrodes move together and each electrode cannot be moved separately.

• Pneumatic system: The most common method for welding systems is to use pneumatic jacks available on the market. These jacks can exert a force of 4 kg on the electrode, corresponding to a pressure of 4 bar per square centimeter of the jack’s cross-section. This method can use two or more stage jacks, which must be custom-made.

Advantages of the pneumatic system: Simplicity in the initial design, rapid results, using market-ready components, and excellent movement speed

Disadvantages of the pneumatic system: Low force generation relative to the occupied space, high friction, high cost of producing suitable compressed air (free of moisture), the need for expensive control equipment to maintain uniform conditions, and high noise pollution.

Hydraulic system: In this method, one-way oil jacks are frequently utilized. Pressure is applied to the jack using a hydraulic pump, and during the return, oil discharge springs are employed.

Advantages: Efficient power generation with a compact design, minimal friction, low noise, reduced maintenance needs, and low power consumption.

Disadvantages: High manufacturing and maintenance costs, significant oil leakage issues, time-consuming electrode gap adjustments, the need for an oil cooling system, and slower operating speeds compared to pneumatics

The criterion for selecting each of these methods is the speed of movement of the electrodes. Mechanical and pneumatic systems are effective for wire diameters up to 8 mm, while hydraulics are better suited for diameters greater than 8 mm.

We have successfully achieved the target speed of 60 beats per minute using a mechanical method.

Mesh sheet pulling system in mesh welding machine

Once a row of cross wires is welded, the mesh-pulling process begins. During this process, after welding a row of cross wires, the line wires are adjusted to the specified size. Similar to the electrode pressure system, the pulling process can be performed using pneumatic, mechanical, or servo motor methods.

• One of the simplest and most convenient methods is using pneumatics. If the criteria for manufacturing a machine are speed and low cost, this method is recommended. Indeed, this method has several shortcomings, including noise generation, impact, limited movement, high energy consumption, and a short lifespan.
• In the mechanical method, the same motor and gearbox that create the pressure on the electrodes can be used to pull the wire. The benefit of employing a mechanical system is smooth, uniform movement. This method is suitable for meshes with fixed openings, such as those used for 3D panel walls that always feature 5×5 openings. It is possible to adjust the pulling force, but it requires time to open and close the crank mechanism.
• Servo motor system: This system is the newest and most common method of wire pulling in mesh welding machines. A servo motor generally includes a motor, a position sensor, like an encoder, and a control system or PLC. This control system obtains the current position from the sensor and compares it to the desired position. The control system issues commands to the motor to reach the desired position. With a servo motor, various pulling operations can be executed, even on a single mesh sheet. For instance, we can have stretches of 4 cm, 6 cm, and 8 cm in a mesh sheet. Before welding the mesh, we enter the dimensions on the monitoring page and adjust the pulling amount for each row of the mesh accordingly. Currently, the best method for a pulling system is to use a servo motor.

Please note that due to the variety of servo motors on the market, the customer’s requirements must first be carefully reviewed to avoid additional costs for the buyer.

PLC System:

In the past, mechanical microswitches were utilized to detect any movement in machinery. These sensors come with both advantages and disadvantages:

1. They are inexpensive and readily available.
2. In some cases, they can be repaired.
3. They issue a command after a brief pause.
4. Their lifespan is limited due to mechanical movement.
5. They do not require a high level of expertise to operate.

Today, most sensors used in machinery are electronic devices that detect changes and transform them into electrical signals. The signal from the sensor is sent to the PLC inputs using connection cables or wirelessly. The PLC processes the input signal according to the program. At this stage, the PLC is capable of performing comparisons, calculations, and decision-making. Based on the processing results, it activates or deactivates relevant outputs, such as starting motors, opening valves, and sending alarm signals.  We aim to produce Mesh Metal machines that operate autonomously, ensuring minimal errors and maximum efficiency. PLC programming is essential to achieving this goal.

Ultimately, these components enable the mesh welding machine to effectively and precisely produce a variety of meshes.