In the class of metal cutting tools, a special place is occupied by devices that perform the functions of nozzles on machines. These include taps that allow the formation of internal threads in metal workpieces.
Despite the simple appearance, this device is a very responsible tool. Suffice it to say that the machine tap is made of special alloys based on high-speed metal or tool steel. As a result, the structure of the material gives the structure a high cutting ability with minor wear processes, which, however, are also inevitable.
Tool purpose
Any tap focuses on the formation of threads in the internal surfaces of various parts. Typically, this tool is considered as an element of the working equipment of machines. So, a typical machine tap is used in processing plants, allowing you to quickly and efficiently implement the task of cutting the desired edge.
At the same time, it is worth emphasizing the variety of thread configurations that this tool implements. Most often, there are techniques for grooving in through and blind holes.
In the first case, a groove is formed along the entire length of the profile channel, and in the second, partially, to a certain point in length. It is noteworthy that the machine tap for blind holes, as a rule, is distinguished by a special chamfer on the working rod. However, the design of the tool should be considered separately.
Tap device
The tool consists of two main parts, which can have different parameters and the overall shape of the structure. The working part is a cylindrical rod, which is both a calibrator and a carver. The second part is the shank, which performs the task of the latch to the installation site in the machine.
By the way, the fastening is realized both through the collet chuck and with the help of special clamping elements - they are also provided in the machine system. For example, machine taps elongated with their lead-in are suitable for installation in axial compensation mechanisms. But there are also manual models that do not integrate into machine chucks, but interact with lever devices that have grooves of a certain format.
It is important to note that the cutting edge itself may have different accuracy. As a rule, the first processing session is performed by draft models, and then more precise, final refinement of surfaces is carried out.
Types of Tap
Typically, tap models are classified into three categories:
- spot;
- uterine;
- special devices.
The first option is used to create threads provided that the passage is processed in one working session. The fallopian instrument has another task - the work of stripping in the holes that were previously serviced by a rough or die tap.
There are also special trenchless models. This is a special category that is distinguished by the principle of thread formation. As a rule, a machine tap without grooves is used in working with soft metals. Processing is carried out by deformation by the roll method, and not by cutting. Thus, for example, the formation of threads is carried out using taps, rollers, eliminating the formation of metal chips.
Main characteristics
There are several parameters by which specialists select the right tool for forming a thread:
- The main characteristic is the nominal diameter of the thread, which can be, for example, 10 mm.
- The thread pitch will depend on the configuration of the location of the grooves . This spacing between the edges can be a few millimeters.
- It should be noted that the machine tap, whose dimensions in diameter are of the order of 10 mm or less, has a harder alloy in its core. Larger models are often made of high-speed metals - modifications whose diameter can exceed 25 mm. But this does not mean that a large-format tap loses in reliability and accuracy of cutting to small analogs. The fact is that an increase in the area of the cutting edges compensates for the lower stiffness indices of the metal structure.
Tips for operating the tap
First of all, you need to choose a tap that is suitable in diameter. Next, the design of its shank is thought out, which should fit the installation site in the cartridge.
If you plan to use a CNC machine, then the optimal speed mode is pre-calculated. In the case of the use of a thread-cutting cartridge, for example, a machine tap should rotate with the expectation that the feed rate per revolution will have an average value of 95% with respect to the step size. This parameter must be set in the machine program. Compliance with this condition will prevent self-tightening of the tool.
Whenever possible, it is recommended to use high-quality cartridges with compensation, which will limit the torque. Thanks to this equipment, a more correct axial movement of the taps is ensured, not to mention their tight control during work operations.
Conclusion
The quality of the thread groove formation is determined by several parameters. This may be the correspondence of the target and processing materials, the correct choice of dimensional values of the tool structure, etc. Often, the characteristics of the result are also affected by the method of exerted effort.
There are taps manual, machine and universal, which are successfully used both in machine tools and in the grip of the clamping device. The most risky method of forming a thread from the point of view of obtaining low quality is a manual tap. This technique entirely depends on how accurately and evenly the forces are applied when grooving. Experienced experts recommend performing such operations slowly, but at a uniform pace throughout the passage.