Thread machining is one of the most important applications for CNC machining centers. The quality and efficiency of thread machining will directly affect the quality of the part and the productivity of the machining center.
With the improvement of CNC machining center performance and the improvement of tools, the thread processing methods are also improving, and the accuracy and efficiency of thread processing are also increasing. antminer s19 pro for saleIn order to enable the craftsmen to reasonably choose the thread processing method during the machining process, improve the productivity and avoid quality accidents, the following is summarized in practice.
1. Tap machining method
1.1 Classification and characteristics of tap machining
The threaded hole processing with taps is the most commonly used processing technology method, which can be mainly applied to threaded holes with different small diameters (D<30) and low level of hole position control accuracy design requirements.
In the 1980s, the threaded hole is tapped by a flexible tapping method, which means that a flexible tapping chuck is used to fix the tap and the tapping chuck can be axially compensated to compensate for the feed error caused by the axial feed of the machine tool and the asynchronous spindle speed to ensure the correct pitch. The utility model has a complex structure, high cost, easy to damage, low processing efficiency. In recent years, the performance of CNC machining centers has gradually improved, and the rigid tapping function has become the basic configuration of CNC machining centers.
Therefore, rigid tapping has become the main method of thread processing.
That is, the tap is clamped by a rigid collet chuck, and the spindle feed and spindle speed are kept consistent by the machine control.
Compared with the flexible tapping chuck, the spring cnc machining manufacturerchuck has a simple structure design, is inexpensive and widely used. In addition to clamping taps, it can also clamp end mills, drills and other tools, which can effectively reduce tooling costs. At the same time, the use of rigid tapping, can be developed to carry out economic high-speed cutting, improve the production and processing technology center main use of work efficiency, reduce the cost of manufacturing companies in China.
1.2 Determination of the bottom hole of the thread before tapping
The processing of the threaded bottom hole has a great impact on tap life and thread processing quality. The diameter of the threaded bottom hole drill is generally chosen close to the upper limit of the threaded bottom hole diameter tolerance,
For example, the diameter of the bottom hole of M8 threaded hole is фф 6.7 + 0.27mm, and the diameter of the drill is ф 6.9 mm, which can reduce the machining allowance of the tap, reduce the load of the tap, and extend the service life of the tap.
1.3 Selection of tap
When selecting taps, first of all, the corresponding taps must be selected strictly in accordance with the materials processed. Tool companies can produce different models of taps according to the different enterprises of the processed materials, and the selection requires special attention.
Because compared with milling and boring tools, taps are very sensitive to the material being processed. For example, using cast iron taps to process aluminum parts can easily cause threaded teeth, random threads and even tap fractures, resulting in scrap. Secondly, the difference between through-hole taps and blind-hole taps should be noted. The front end of through-hole taps is longer, and the chips discharged are front-end chips. The front end of the blind hole is shorter and the chip is discharged as the back chip. Machining blind holes with through-hole taps does not guarantee the thread machining depth. In addition, if a flexible tapping chuck is used, the diameter and square width of the tapping shank should be the same as the diameter and square width of the tapping chuck, and the diameter of the tapping shank used for rigid tapping should be the same as the diameter of the spring bushing. In short, only a reasonable choice of taps can ensure the smooth processing.
1.4 CNC programming of tap machining
The programming of tapping processing is relatively simple. The current machining center generally curing tapping subroutine, only need to assign a value to each parameter. However, it should be noted that different CNC systems, different subroutine format, the meaning of some parameters are not the same.
For example, SIEMEN 840C control management system, it is the programming language format: G84 X_Y_R2_ R3_R4_R5_R6_R7_R8_R9_R10_R13_. Only these 12 parameters need to be assigned during programming.
2. Thread milling method
2.1 Characteristics of thread milling
Thread milling is the use of a thread milling tool, machining technology center three-axis linkage, that is, X, Y-axis circular interpolation, Z-axis linear feed milling method as well as processing the product thread.
Thread milling is mainly used to process large hole threads and threaded holes of difficult-to-machine materials. It mainly has the following characteristics:
(1) Fast processing speed, high efficiency and high machining accuracy. Generally the tools are carbide, and the cutting speed is fast. The tool is manufactured with high precision, so the milling thread is highly accurate.
(2) The milling tool selection applies to a wide range of studies. As long as the pitch is the same, whether it is left-hand thread or right-hand thread, it is possible to carry out the use of its own one tool, which is beneficial to the enterprise to reduce the tool management cost.
The milling process is easy to chip removal and cooling, and the cutting conditions are better than taps, especially for thread processing of difficult to machine materials such as aluminum, copper and stainless steel. It is especially suitable for thread processing of large parts and precious materials, which can guarantee the quality of thread processing and the safety of the workpiece.
(4) Since there is no tool front guide, it is suitable for processing short blind holes in the bottom hole of threads and holes without drawing slots.
2.2 Classification of thread milling tools
Thread milling tool material can be divided into the following two types, one is machine clamped carbide insert milling cutter and the other is integral carbide milling cutter. The machine-clamped tool selection is applicable to a wide range of studies, which can improve both the processing of holes with thread working depth influence less than the length of the insert and the processing of holes with thread depth learning greater than the length of the insert. Integral carbide milling cutters are generally mainly used to produce holes where the thread depth data is less than the tool path length.