Trapezoidal thread is widely used for the manufacture of various screws that are used for various production equipment. For example, for machine tools, lifting devices, presses. Such a thread has the form of an isosceles trapezium, and the profile angle can have different values: 15, 24, 30, 40 °. In the process of the screw, on which the trapezoidal thread is cut, there appear friction forces caused by natural means. That is, due to the presence of a lubricant, surface roughness, and profile angle.
Types of thread
Today there are such types:
- Metric. It serves to secure multiple items. Conditions of cutting are set in the regulatory documentation. The profile is a triangle with equilateral angles. This figure is 60 °. Metric screws are made with small and large steps. The first type is used for fixing sheet elements to create increased tightness. This type of attachment can be found in precision optical devices.
- Conic. It is made the same as the previous view, but the twisting is made to a depth of 0.8 mm.
- Inch. To date, there is no regulatory document, which would indicate the size of the thread. Inch thread used in the repair of various equipment. As a rule, these are old instruments and devices. Its main indicators are the outer diameter and pitch.
- Pipe cylindrical. This species is an isosceles triangle, the upper angle of which is 55 °. This internal thread is used to connect pipelines, as well as parts made of thin sheet material. It is recommended when there are special requirements for the tightness of the connection.
- Pipe conical. Female thread must comply with all regulatory requirements. Dimensions are fully standardized. It is used to attach various types of pipelines.
- Resistant Such a view is an unequal trapezium, where one side is inclined by 3 ° and the other by 30 °. The first side is working. The shape of the profile, as well as the diameter of the steps are determined by regulatory documents. In accordance with them, the thread is made with a diameter of from 10 to 600 mm, with the maximum pitch value being 24 mm. They are used where increased holding forces are required.
- Round. The thread profile is a variety of arcs connected by straight lines. Profile angle is 30 °. This type of thread is used for those compounds that are affected by aggressive media.
- Rectangular. It is not fixed by any regulatory documents. Its main advantage is high efficiency. Compared with the trapezoid view, it is less durable, and also causes a lot of incomprehensible moments in its production. The main place of application - jacks and various types of screws.
- Trapezoidal. Has the shape of an equilateral trapezoid with a profile angle of 30 °. Trapezoidal thread, the dimensions of which are fixed in the documentation, is used to connect the various elements of production equipment.
Compared with other types of trapezoidal thread is much easier to manufacture.That is why it is often used in various fields. The most popular is a screw with trapezoidal thread, having a profile angle of 30 °. The production technology is very similar to that used for cutting rectangular threads. But there are still significant differences regarding the accuracy and purity of production. Trapezoidal threading is no different from the same procedure with a rectangular view. At the moment there are several such methods.
Screw production with one cutter
Single-thread trapezoidal thread is made as follows:
- preparation is prepared and channels for sharpening are induced;
- sharpening the cutter using a specially prepared template;
- installation and fixing of the sharpened element It should be located so that the centers coincide and are parallel to the axis of cutting;
- the equipment is turned on and the workpiece is supplied for threading;
- the finished part is checked in accordance with the finished template.
Cutting with three incisors
This method consists in the following:
- preparation is prepared;
- sharpening three cutters - straight, narrow and profile;
- the installation and fixing of the prepared elements is carried out. They can be located both perpendicularly and parallel to the axis of the thread. It all depends on the angle of inclination.
Common Production Method
It is in the production of trapezoidal threading goes like this:
- working equipment is checked and adjusted;
- thanks to the slotted cutter, small recesses on the screw are made;
- using a narrow slotted element, a screw is cut to a certain diameter;
- with the help of the profile slotted element, the final manufacture of trapezoidal threads is performed;
- finished part is checked in accordance with ready-made templates.
Trapezoidal thread: sizes
As mentioned earlier, this type of thread has a trapezoid shape, in which the angle between the sides can have different values. All main dimensions are installed in accordance with GOST.For single-thread type, trapezoidal thread (dimensions - GOST 9481-81) has dimensions and steps of various diameters - from 10 to 640 mm. In addition, it can be multiple, as well as swirling to the left or right side. These indicators are normalized by GOST 24738-81.
For the functioning of any element, such as a machine or mechanism, it is necessary to fulfill a mandatory condition: rotational motions must be transformed into translational.This principle is used for the manufacture of various machines, devices, control systems used in the industrial field.
The effectiveness of the work on the transformation of rotational movements into translational is carried out with the help of a nut and a screw. Despite the fact that these parts look simple, they require care in their manufacture. It is on these parts that the performance and reliability not only of the component elements, but also of the entire working equipment depends.
Trapezoidal thread has proven itself only on the positive side. That is why it is used in various devices.
Features multiple thread
In order to give the screw with strength characteristics and increase its stroke, multiple trapezoidal threads are used. In this case, all parameters, such as the height of the thread, its diameter is absolutely identical, with a single-turn view. The only difference is the number of moves for one step. For example, three-way thread types have a stroke three times as large as their pitch. All this can be seen in the figures.
Let us give an example so that this view becomes understandable to everyone. All use conventional lids for canning vegetables and fruits. To open them you need to make a minimum of effort. When using cylinders of large diameters to get into the grooves of a one-way thread is much more difficult. That is why use multi-pass.
This type of thread can be determined visually, just look at the picture.You can see how many turns go from the beginning of the screw. Multi-way threads are manufactured using sophisticated technology, and therefore cost more.
Trapezoidal compounds possess many positive qualities. That is why they are used in various industrial sectors. The most common area is engineering. So, their advantages include the following:
- the ability to assemble and disassemble various devices an unlimited number of times;
- convenient process of analysis and assembly;
- the reliability of the threaded connection;
- easy manufacturing process;
- independent regulation of the compression force;
- manufacture of parts in various designs.
Lack of connections
The negative sides of this type of connection is not so much. One of them is the occurrence of a large tension in the cavities. In addition, they cannot be used in devices and mechanisms that have a high vibration, since the screws can loosen themselves, which is not a good sign.Therefore, it is necessary to monitor this, and in the event of such a situation - to correct the position of the screws.
Such quality as cost can be attributed to both positive and negative sides.One-way threads are significantly lower than multi-way threads. Here everyone chooses according to personal preferences. Many design organizations use precisely multi-thread threads, as they are distinguished by reliability and durability.
So, we found out what a type of connection is, such as trapezoidal thread, its dimensions, advantages and disadvantages.