M10-thread: how is it?
One of the achievements, which played an important rolerole in accelerating scientific and technological progress, distinguishing the last 500 years of human history, is the invention of a threaded joint. Let's take a closer look at its features.
Rivets and wedges
In ancient times, the strength of prefabricated structureswas given by such means of joining as wedges (in wooden products) and rivets (in metal products). The main drawback of such connections has been and remains the inability to reuse fasteners.
Wedges and rivets are disposableuse, and this requires unnecessary costs. The first threads also had a significant limitation, because they were not made on the cutting machines, but by means of patterns, with which the thread was forged on a hot metal. On the interchangeability of parts that had an external and internal thread, made in this way, it was not.
Metric thread
In most countries of the world, a metrica measurement system based on the conventionality that one meter is a thousand millimeters. This system of measurement and the production of machines that were gaining momentum led to a wide distribution of metric threads and the simplicity of its designation. For example, the designation M10 (thread) - here the letter "M" indicates its diameter in metric system measurements.
However, these are not all the parameters that characterize a threaded connection. In this case, in the characteristic "thread M10", the diameter is indicated by the number 10, it indicates outer diameter on bolt. In addition to the thread diameter, there is another indicator, such as the thread pitch.
Depending on the strength of the connection, the thread pitch can be different. Thus, the standard thread M10 can have the following step values:
- 0,5 mm;
- 0,75 mm;
- 1 mm;
- 1.25 mm.
For the largest standard thread, the step in itsThe designation can not be specified, because it is taken as the main one. So, if we see the designation M10, and after that there are no additions, then by default this M10-thread has a step of 1.25 millimeters.
Internal metric thread
Naturally, in order for the threaded connection to be applied, two threads must be combined, cut in the corresponding places of the parts to be joined:
- external - on a bolt or hairpin;
- Internal - in the nut or body of the part.
In the detail in which the internalthread M10, the hole must be drilled in accordance with the length and pitch. This diameter is often easy to compute with elementary knowledge in mathematics and even not having tables with standard values at hand, since the standard for the thread in the metric system has a profile angle of 60 degrees.
The rules of an isosceles triangle and the theoremPythagoras allow you to easily determine that the height of the thread in steps of 1 millimeter will be equal to 0.866 millimeters. Thus, the hole in which the M10-thread will be created must be at least 8.268 mm:
10 - 0.866 - 0.866 = 0.8268
Since the thread is on both sides of the drilling axis, the thread height is taken from the outer diameter twice.
Why there is a different step
As mentioned earlier, depending on theThe required thread strength is a different thread pitch. The most common among those used in engineering and other fields is a major step. However, for a higher strength of the connection, a small thread pitch is also used.
It, in addition, is used also whererequires greater accuracy. For example, in a measuring instrument of higher accuracy than a caliper, a metric thread with a small or very small thread pitch is used. In this case, the translational movement, the size of which needs to be measured, is divided into the length of the thread circumference, which makes it possible to measure not only tenths but also hundredths of a millimeter.
Naturally, a large thread pitch will preventaccurate measurement. After M10-thread with a large step of 1.25 millimeters will have a measuring accuracy of two and a half times smaller than with a very small step of 0.5 millimeters.
It is worth noting that due to the more complex (from the point ofview of technology) of getting a thread with a very small step, it is practically not used in engineering. The main area of its application is a measuring instrument.
Although most threaded joints haveright thread (to tighten the bolt, it needs to be rotated clockwise), if necessary, the left one can be used. For example, a bicycle pedal kit has a left and right mounting thread.
