Thu Jun 09 10:06:19 CST 2022
Next, we will elaborate on the transmission structure, guide rail structure, and driving method of the workbench of the wire cutting machine tool.
The accuracy of the screw is of course important, but if the installation structure of the screw is unreasonable, no matter how good the screw is, it will not help.
First of all, look at the form of the screw to see if it is a ball screw, a triangular screw or a trapezoidal screw. On the wire cutting machine, the ball screw is better than the triangular thread screw and the trapezoidal thread screw, and the diameter of the screw is required to be as large as possible to increase the rigidity. It is best to use such accessories from well-known companies.
The second is the installation structure of the lead screw. The ball screw is a precision transmission component. Therefore, in order to give full play to its precision, the assembly structure of the lead screw has high requirements. It must be fixed at both ends and supported by shafts. For large-stroke machine tools , but also pre-stretch the lead screw to reduce the deflection of the lead screw, thereby improving the motion accuracy of the machine tool table.
(1) First of all, it is necessary to understand the number of gears in the gearbox in detail. The more gears that participate in the transmission, the greater the transmission resistance, the easy to wear the tooth surface, and the transmission is prone to gear gaps, resulting in the greater the systematic error of the machine tool table, and the more gears. Poor assembly is also prone to accidental errors, so the fewer transmission gears, the better, and the use of a pair of gears will minimize the transmission error. Therefore, it is very important to have a deep understanding of the gear transmission structure of the table movement during model selection.
(2) Carefully observe the working environment and lubrication performance of the transmission gearbox of the workbench. 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 cutting fluid for a long time. This design is very unreasonable, and the light ones increase the wear of the gears. In severe cases, the stepping motor will be burned out by water, so the user must observe the position of the gear box of the worktable when selecting the model to ensure that the cutting fluid must not be immersed, which is very important for the accuracy of the machine tool.
(1) The guide rail is the key to ensure the movement accuracy of the worktable, and the user should pay great attention to it when selecting the model. First, observe the size of the cross-section of the guide rail. Under the same conditions, the thicker the shape, the better the rigidity, and the less likely it will be deformed during processing. Secondly, learn about the material and heat treatment process of the guide rail from the manufacturer. Generally speaking, in order to ensure its strength and small deformation, it is better to use high-carbon alloy steel, integral quenching or audio-frequency quenching process.
Directly observe the guide rail structure. At present, the common guide rail structures on the market are as follows:
Inlaid steel ball rolling guide;
Inlaid steel roller type rolling guide;
Linear rolling guide;
Elastomeric bearing cast iron rails.
The difference between the first type and the second type is that on the rollers of the guide rail, one is a ball and the other is a roller. The ball and the guide surface are in point contact, and the roller and the guide surface are in line contact, so its wear resistance and bearing capacity are much better than those of the ball type, while the elastic bearing guide is a simple guide and is eliminated. Users should consider the third structure as much as possible when selecting models. At present, the wire travel has completely inclined to the third structure.
Wire-cutting machine tools are generally driven by stepper motors. In stepper motors, there are reactive and hybrid types to achieve different step angles. The most common on the market is reactive stepper motors. The reactive stepping motor has different driving modes such as three-phase three-beat, three-phase six-beat, five-phase ten-beat, and five-phase double-ten-beat. 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-beat will gradually replace the three-phase six-beat. This is because the five-phase ten-beat not only subdivides the step angle of the three-phase six-beat, but also increases the motor winding to five-phase, so the transmission is stable and the force is large. There has been some progress in the past two years. For example, the major domestic wire-feeding manufacturers have begun to use the five-phase double ten-beat drive method, which has improved the drive performance to a new level.
To sum up, in order to ensure the long-term reliability of the machine tool when selecting a wire cutting machine tool, the user should choose the following structure:
(1) Use 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 worktable should be less, preferably a pair of gears, and the position structure of the gear box ensures that the cutting fluid cannot be immersed;
(3) Try to choose a linear guide with a large cross-sectional area or a large width-thickness ratio;
(4) Select the five-phase double ten-beat stepping motor drive mode, and it is more ideal to choose the AC servo drive if conditions permit.
Due to the large processing range and strong bearing capacity of the large-sized wire cutting machine tool, foreign machine tools cannot be compared with it when processing large molds, so the benefits it can create are considerable, but if there is a problem with the machine tool, especially There is a problem with the memory quality of the machine tool itself, and the losses caused by it are also heavy. Therefore, special care must be taken for the selection of large-scale wire-cutting machine tools.
Due to the characteristics of large stroke and large load, the structure and rigidity of the machine tool should be considered in the selection of models, so that the accuracy can be reliably guaranteed during the processing of large workpieces. The difference:
(1) The worktable must adopt a full support structure to improve the rigidity of the machine tool to ensure heavy load without deformation.
(2) Imported linear guides are used to ensure good sensitivity and motion accuracy under heavy loads.
(3) The diameter of the ball screw must be larger than that of the small machine tool.
(4) If the user has a certain strength, the worktable of the machine tool is best driven by an AC servo motor, which is characterized by accurate precision, fast movement speed, high reliability and convenient operation.