In the class of metal-cutting tools, a special place is occupied by devices that perform the functions of nozzles on machine tools. These include taps that allow you to form an internal thread in metal blanks.
Despite its 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 endows the design with high cutting ability with minor wear processes, which, however, are also inevitable.
Instrument assignment
Any tap focuses on the formation of threads in the internal surfaces of various parts. Usually this tool is considered as an element of the working equipment of machines. So, a typical machine tap is used in processing installations, allowing you to quickly and efficiently implement the task of cutting the desired edge.
It is worth emphasizing the variety of thread configurations that this tool implements. Most commonly, a distinction is made between grooving techniques in through and blind holes.
In the first case, a groove is formed along the entire lengthprofile channel, and in the second - partially, up to a certain point in length. It is noteworthy that a machine tap for blind holes, as a rule, has 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 in general form of construction. The working part is a cylindrical rod, which is both a calibrator and a cutter. The second part is the shank, which performs the task of fixing to the installation site in the machine.
By the way, fastening is realized both through a collet chuck and with the help of special clamping elements - they are also provided in the machine system. For example, machine taps with their lead length are suitable for installation in axial compensation mechanisms. But there are also manual models that are not integrated 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 can have different accuracy. As a rule, the first processing session is carried out with draft models, and then more precise, finishing surfaces are carried out.
Types of tap
Normally tap models are classified into three categories:
- flatbed;
- uterine;
- special devices.
The first option is used to create a thread subject to processingpassage in one session. The mother tool has a different task - to perform cleaning in holes that were previously served by a rough or flat tap.
There are also special grooveless models. This is a special category that differs in the principle of thread formation. As a rule, a machine tap without grooves is used in working with soft metals. Processing is performed by rolling deformation, and not by cutting. Thus, for example, the formation of a thread is carried out using taps-formers, which exclude the formation of metal chips.
Key Features
There are several parameters by which specialists select the right tool for threading:
- 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 grooves. This distance between the edges can be several millimeters.
- It should be noted that the machine tap, whose dimensions in diameter are about 10 mm or less, has a harder alloy at its core. Larger models are often made of high-speed metals - modifications whose diameter can exceed 25 mm. But this does not mean at all that a large-format tap loses in reliability and cutting accuracy to small analogues. The fact is that the increase in the area of the cutting edges compensates for the lower rigidity of the metal structure.
Tap Tips
First of all, you need to choose a tap that is suitable for the diameter. Next, the design of its shank is thought out, which should fit the place of installation in the cartridge.
If you plan to use a CNC machine, then the optimal speed mode is also pre-calculated. In the case of a tapping chuck, for example, a machine tap must be rotated with the expectation that the feed rate per revolution will have an average value of 95% in relation to the pitch value. This parameter must be set in the machine program. This condition will prevent the tool from self-tightening.
Also, whenever possible, it is recommended to use high quality chucks with compensation, which will limit the torque. Thanks to this equipment, a more correct axial movement of taps is ensured, not to mention their tight control during work operations.
Conclusion
The quality of thread grooving 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 design, etc. Often, the characteristics of the result are also affected by the method of exerted effort.
There are hand taps, machine taps and universal taps that are successfully used both in machine tools and in the clamping device. The most risky thread forming method in terms of getting poor quality ismanual tap. This technique is entirely dependent on how accurately and evenly the forces are applied when cutting grooves. Experienced experts recommend that such operations be performed slowly, but at the same pace throughout the entire passage.
