In the mold processing, the middle wire cutting process is generally the final process, so the machining accuracy is very high. If the mechanical precision of the machine tool is not good, it will directly affect the processing quality of the product and the mold, eventually leading to loss of users and loss of market. When selecting the middle wire cutting machine, how to judge the mechanical precision and structure, the advantages and disadvantages are very important. Below we will elaborate on the transmission structure, guide rail structure and driving method of the wire cutting machine table.
1.Screw and its mounting structure
The precision of the lead screw is important, but if the mounting structure of the lead screw is unreasonable, no matter how good the lead screw is, it will not help. Therefore, first check the form of the lead screw to see if it is a ball screw or a triangular thread screw or a trapezoid. Threaded screw. On the online cutting machine, the ball screw is superior to the triangular threaded screw and the trapezoidal thread screw, and the diameter of the screw is required to be as large as possible to increase the rigidity. Such accessories are preferably used by well-known enterprises.
Secondly, the mounting structure of the screw and the ball screw are precision transmission parts. Therefore, in order to give full play to its precision, the assembly structure of the screw is also required. It must be fixed at both ends and supported by the shaft. The lead screw is also pre-stretched to reduce the deflection of the lead screw, thereby improving the movement accuracy of the machine table.
2.Gear transmission structure
(1) Firstly, the number of gears in the gearbox should be known in detail. The more gears that participate in the transmission, the greater the transmission resistance, the easy to wear the tooth surface, and the gear gap is easy to be generated, resulting in a larger system error of the machine table and more gears. If the assembly is not good, it is easy to produce accidental error, so the less the transmission gear, the better, the minimum error is caused by a pair of gear transmissions. Therefore, it is very important to understand the gear transmission structure of the table movement during the selection.
(2) Carefully observe the working environment and lubrication performance of the worktable transmission gear box. Due to the unreasonable design of the early machine tools of some manufacturers, the cutting fluid can easily enter the gear box, so that the gears work in the immersion of the cutting fluid for a long time. This design is very unreasonable, and the lighter increases the wear of the gears. The heavy one causes the stepping motor to burn out in the water, so the user must observe the position of the workbench gear box when selecting the type to ensure that the cutting fluid must not be immersed, which is essential for the accuracy of the machine tool.
3. The rigidity and overall structure of the guide rail
The guide rail is the key to ensure the accuracy of the worktable. Users should pay great attention to the selection. First, observe the cross-section of the guide rail. Under the same conditions, the thicker the shape, the better the rigidity, and the more difficult it is to deform during processing. Secondly, the material and heat treatment process of the guide rail are known to the manufacturer. In general, in order to ensure its strength and small deformation, high carbon alloy steel, integral quenching or over-audio quenching process is better. The common rail structures currently on the market are as follows:
1 inlaid steel ball type rolling guide;
2 inlaid steel roller type rolling guide;
3 linear rolling guides;
4 elastic bearing cast iron guide.
The difference between the first type and the second type is on the roller of the guide rail, one is a ball and the other is a roller. The ball is in point contact with the rail surface, and the roller and the rail surface are in line contact, so its wear resistance and bearing capacity are much better than the ball type, and the elastic bearing rail is a simple guide rail and is eliminated. The user should try to consider the third structure when selecting the type. At present, the middle wire has completely inclined to the third structure.
4. The driving method
The middle wire cutting machine is generally driven by a stepper motor. In the stepping motor, there are different types of reactive and hybrid, to achieve different step angles. The most common type of reactive stepping motor on the market is The reactive stepping motor has different driving modes such as three-phase three-shot, three-phase six-shot, five-phase ten-shot, five-phase double ten-shot. The three-phase motor has a large step angle and only three-phase windings. With the continuous improvement of market demand and the improvement of the overall level of the machine tool industry by the relevant departments of the Ministry of Machinery Industry, the five-phase ten-shot will gradually replace the three-phase six-shot. This is because the five-phase ten-shot not only subdivides the step angle of the three-phase six-shot, but also increases the motor winding to five phases, so the transmission is smooth and powerful. In the past two years, there have been some progress. For example, the main domestic wire-cutting manufacturers have begun to use the five-phase and double-shot driving methods, which has improved the driving performance by one level.
Through the above analysis, everyone should know how to look at the price of the wire? In summary, the user should choose such a structure to ensure long-term reliability of the machine tool during the selection of the middle wire cutting machine:
(1) Select a precision ball screw with a diameter as large as possible, and have a fixed bearing support structure at both ends;
(2) The transmission gear of the workbench should be less, preferably a pair of gears, and the positional structure of the gearbox ensures that the cutting fluid must not be immersed;
(3) Try to use linear guides with large cross-sectional area or large width-to-thickness ratio;
(4) Select the five-phase double ten-step stepping motor drive mode, if the condition is selected AC servo drive is more ideal.
