Diameters for cutting external taper threads. How threading is performed, and the choice of a tap for cutting. Scope and tools

The tapered thread and its designation in the presented table must comply with the established state GOSTs, since it is used to create strong connection pipes, where available high pressure or external high mechanical loads are imposed. Examples of application include factors such as:

1. Obtaining a strong connection of pipes that are laid under a dirt road at a shallow depth, the whole point is that loads are placed on them by means of vehicles passing along the road.
2. Also, conical threads are used to connect pipelines in places where welding cannot be used or it is not possible to use it. It can be an explosive environment, which excludes the possibility of using welding equipment.
3. In addition, it is used in cases where the thread has signs of wear or it is not possible to completely replace given element. But it is worth noting that this type of product is of a non-permanent nature, since the replacement of a worn element is an inevitable measure.

It is mainly used for sealing pipes used in the laying of water and gas pipelines, making the connection more reliable even under the most extreme conditions.

Short description

A pipe taper thread is a special type of thread that is similar in shape to a cone, that is, a decrease in diameter towards the end of the part. The profile of such a connection should only have an angle of 55 degrees, and the cutting itself has troughs and vertices of a rounded shape.

In this case, the pitch is indicated by the corresponding number of turns per inch and they are cut at a slope of 1 ° 47'24 ", which, in turn, should correspond to a taper of 1:16. The reliability of cohesion lies in the fact that the more turns, the higher the tightness.

In addition, there is a metric conical thread in the connections of an external cone-shaped with an internal cylindrical one with a designated profile, which, according to GOST 9150-2002, must have flat-cut cavities.

One of its main advantages is that taper threading can be carried out directly on site using threading dies or die cutters. But in order to make the right cut, it is necessary to use special pipe tesks, since the torque during the creation of the grooves is quite large.

Also used in accordance with GOST 6111-52 conical inch thread. It is designed to combine fuel, oil, hydraulic and air pipelines in mechanical engineering. As for the difference from the usual cone-shaped one, it lies in the fact that in this case there is no reference to the cutting step, but is measured by the number of revolutions per unit length.

The name itself means that its dimensions are indicated in inches, since it refers to the English measurement system, for example, 1/8, 1/4, 1/2 inches.

Specifications

According to the state standard, pipe conical threads must directly meet such requirements as:

• The profile angle must necessarily correspond to 55 degrees.
• To different diameters uses its own cutting step.
• Mandatory observance of the angle of deviation of the conical surface from the axis of the pipe itself, regardless of its diameter. The slope is performed in a ratio of 1:16.
• The use of welding equipment or connecting flanges is only applicable for large pipe diameters. The maximum possible diameter is 6 inches.
• In addition, it is required to observe the ratio of the total working length with working cut.

Therefore, it is very important that the drawing fully complies with the established state standards, since such fittings are used at points with high blood pressure and temperatures, which, in turn, allows maximum sealing of pipeline parts if necessary.

Dimensions according to GOST 6211-81

Designation on the drawings

Due to the fact that when using pipe tapered threads, different types such adhesions, it is properly necessary to know the dimensions. According to GOST 6111-52, dimensions are indicated by a fraction, where the denominator is the outer diameter, and the numerator is its inner diameter.

Pipe designations taper thread in the drawing are represented by such letters as:

1. R - designation of a conical thread with an external thread.
2. Rc - indicates the conical internal grooves.
3. Rp - internal thread of a cylindrical profile.
4. LH - cutting with a left-handed spiral.
5. RH - with the right helix.
6. MK - metric cone.
7. M - metric.
8. K - conical inch thread.
9. Pipe conical thread - To pipes ½ GOST 6211-69.
10. With a shortened profile - To pipes ½ reproach GOST6211-69.
11. Shortened conical with increased accuracy - To pipes ¾ pov. toch. GOST 6211-69.

Cylindrical threads are used directly together with external taper threads, which have the same pitch.

Profile and Dimensions of 60 Degree Tapered Inch Threads

This table shows what deviations can be in slope and profile step.

Video: taper pipe threading.

Concerning additional fasteners, then cotter pins are often used as connecting parts, since pipelines can be subjected to vibration, both constant and periodic.

The thing is that this type of connection tends to unwind, then in order to avoid this, cotter pins are used for such connections. This is especially true for places where pipelines are laid under highways, where there is a constant movement of vehicles, which creates vibrations.

Very extensive. Even if we consider a separate case, for example, a pipe thread in the shape of a cone, then here we cannot do without clarifying its features and types. wide enough, allowing you to create reliable tight connections without welding. They are even called universal, since this is the only type of screw thread that allows connection to pipes of other shapes and sections.

Types and classification: inch Fanuc and others

According to the shape of the surface of the pipe on which the thread is made, it can be:

• Cylindrical - traditional cutting on rolled products of constant diameter;
• Conical - here the base is a conical pipe, that is, one with outside diameter to the end gradually decreases.

In this case, internal and external screw threads are distinguished in accordance with its location on the walls. There can be only one purpose: the pipe internal conical thread, like the external one, forms fastening and sealing joints.

According to the attached measurement system, pipes with threads of two types are produced:

• profile angle 60º) - the most common type of connections used in our country in the manufacture of new equipment.
• , whose outer diameter and other parameters are tied to the English system of measures, that is, they are expressed in inches. The conical inch thread is different in that it is not tied to the threading step. Instead, the number of turns per unit length is used.

The direction of the turns can be right, less often - left. You should also take into account the number of their visits.

• Normal

For diameters from 1" to 6", 11 threads per inch are more commonly used.

• small

Is different large quantity turns per unit length due to reduced cutting pitch. This is done to maintain the thickness and strength of the walls, maximum tightness of the joints or fine adjustment relative position details.

For pipes no larger than an inch (½ʺ and ¾ʺ) take 14 turns, but cutting 19 and 28 threads is possible withdfrom 1/16" to 3/8".

Tapered threads and their applications: internal with standard gauge and natural torque

Tapered pipe threads are widely used in the creation of pipelines operating under pressure (water supply, heating, fuel lines and gas pipelines), since they provide tight connections even at pressures of tens of MPa.

When talking about the versatility of conical threading, they mean the possibility of its installation together with cylindrical couplings. This type of connection has to be resorted to when connecting to pipes in which the internal thread is partially destroyed or deformed, and it is not possible to replace the defective section or solve the problem by welding.

Of course, in this case, the contact between the two pipes will be minimal - only in the part where the diameter of the cone and cylinder coincide. There is no need to talk about reliability, therefore the method is considered only as a temporary measure.

However, subject to established norms interchangeability in accordance with GOST 6357-81, an internal cylindrical pipe thread can go in conjunction with a conical thread. But in this case, the screw-in length of the individual elements, the diameter tolerances and the accuracy class must be observed.

Tapered pipe thread standards according to GOST 6211 81: diameter and other dimensions

Giving a classification of connections, we deliberately did not touch on the whole variety of threaded profiles. Because only a triangular shape is suitable for cutting a screw on conical pipes - the most reliable and durable. True, it has several options for the execution of the top and bottom of the threads, depending on the standards used. And this is where the differences are possible.

The so-called British pipe taper thread has a triangle profile with rounded teeth and reciprocal troughs (BSPT standard). This allows it to be used simultaneously with liquid sealants and sealing tapes. In addition, rounded edges perfectly hold dynamic loads. The angle α at the apex of each triangle is 55º, and all dimensions are given in inch standards.

Domestic analogue - GOST 6211 81 strictly regulates the parameters of an inch conical profile:

• slope towards center line pipe (taper) is kept at 1:16. At the same time, its length and the selected size of the section do not play a role.
• The cone connection is only allowed for pipes whose diameter does not exceed 6”, so the thread also has appropriate size restrictions.

In the NPT profile, the isosceles triangular turns (α=60º) have flat tops with the same reciprocal bases. Screw cutting is performed in accordance with American standards UNS (coarse pitch), UNF and UNEF (fine and extra fine). Here is a more modest choice of diameter: from 1/16' to 4 inches. For this type of connections, we have developed a separate GOST for taper thread 6111-52 (inch) and GOST 25229-82 (metric).

A screw with a profile angle of 60º works on crushing, creating a tight, but one-piece connection. It is used in mechanical engineering and machine tool building for pipelines in which fuels and lubricants, water or gaseous working media under pressure circulate. Tapered pipe threads are able to withstand the maximum possible pressure.

Designations: tap, drawings

GOST for tapered threads provides the following designations:

• R or Rc - external or internal. The nominal diameter, expressed in inches, must be indicated next.
• LH - left. If the taper thread is right-handed, this marking is absent in the designation (default setting).
• Rp - indicates cylindrical shape internal thread compatible with outer cone.

The American designation for taper pipe threads is more complicated, but more informative. In addition to specifying the position of the thread (MNPT - external, FNPT - internal), the following parameters are indicated in the marking:

• nominal diameter;
• number of turns per unit length;
• group according to the type of profile execution;
• accuracy class for external (A) and internal cutting (B).

WATCH VIDEO

The diameter is specified in inches by a fraction or by an assigned number. Tapered pipe threads are often used in utility connections. cone inch pipe one of the most popular in high pressure areas.

The standard establishes the diameters of holes for cutting pipe taper threads in accordance with GOST 6211-69 in steel products in accordance with GOST 380-71, GOST 4543-71, GOST 1050-74, GOST 5058-75 and GOST 5632-72 (except for nickel-based alloys) and copper according to GOST 859-66.

TAPPING HOLES
PIPE CONICAL THREAD

DIAMETERS

GOST 21350-75

STATE STANDARDS COMMITTEE
USSR COUNCIL OF MINISTERS

Moscow

DEVELOPED, INTRODUCED AND PREPARED FOR APPROVAL by the All-Union Research Institute for Normalization in Mechanical Engineering (VNIINMASH)

And about. directors Gerasimov N.N.

Theme leader and performer Zaroslova M.P.

APPROVED AND INTRODUCED BY Decree State Committee standards of the Council of Ministers of the USSR of December 12, 1975 No. 3877

STATE STANDARD OF THE UNION OF THE SSR

By the Decree of the State Committee of Standards of the Council of Ministers of the USSR dated December 12, 1975 No. 3877, the validity period is established

from 01.01.77

1. This standard establishes the diameters of holes for cutting pipe taper threads according to GOST 6211-69 in steel products according to GOST 380-71, GOST 4543-71, GOST 1050-74, GOST 5058-75 and GOST 5632-72 (except for alloys on nickel-based) and copper according to GOST 859-66.

2. Hole diameters with taper reaming and their limit deviations must match those shown in Fig. 1 and in table. one.

Table 1

Dimensions in mm

Note. For threads with nominal size over 2² nominal hole diametersd o and their limit deviations must be equal to those established by GOST 6211-69 for the inner diameter of the thread.

3. Diameters of holes without reaming into a cone and their maximum deviations must correspond to those indicated in Fig. 2 and in table. 2.

4. It is allowed to use holes of other diameters obtained on the basis of experimental data for taper pipe threading.

5. Drill diameters for tapping holes are indicated in the recommended.

table 2

Dimensions in mm

Drill diameters for taper pipe threads

Dimensions in mm

Nominal thread size in inches	Number of threads per 1²	Step R	Hole drill diameter
			with cone reaming	without cone reaming
1 / 8		0,907
1 / 4		1,337	10,8	11,1
3 / 8			14,25	14,5
1 / 2		1,814
3 / 4			23,25
		2,309
1 1 / 4				38,25
1 1 /2
				Threading is one of the most common operations in metalworking. For its implementation in non-serial production, universal screw-cutting lathes are used. These machines work with workpieces in the form of bodies of revolution and small non-symmetrical parts that can be mounted on the faceplate of the machine. In other cases, the thread is obtained by milling, rolling and other methods. Threading cutters have inserts made of high speed steels and hard alloys as a cutting edge. For preliminary operations, plates made of alloys T15K6, T14K8 and their analogues are used, and for finishing - T30K4 and T15K6. In the processing of cast iron blanks high efficiency show elements from V2K, VK3M, VK4, VK6M alloys. Internal thread cutting For internal thread in addition to cutters, taps and combs are used. The tap is a tool in the form of a threaded rod made of hardened steel. On the surface of the rod along its axis there are milled grooves, due to which the thread has cutting edges. The tail part of the tap has square section, which allows you to fix it in a chuck or collar. During threading, the metal is not only sheared into chips, but also plastically deformed due to the plunge of the tool, and the inner diameter of the hole increases. Taking into account this feature, the diameter of the hole for the thread is calculated by subtracting the thread pitch from the outer diameter of the tap. There are many different taps, of which nut, manual and machine taps are widespread. For threading with a tap, the part is fixed on the machine, a hole is drilled in it and the spindle is adjusted to the required number of revolutions. The tap, installed in the tailstock, is inserted into the hole due to the movement of the quill, and the part rotates. taper thread cutting Of the conical threads, the most widely used is the standard one, which has a profile that is symmetrical with respect to the normal to the axis of the cone. To cut such threads, the same methods are used as for ordinary cylindrical threads. For external taper threads, the outer diameter is turned into a cone. This is easy to do with threaded cutters on a screw-cutting lathe using a copy ruler, but this method is characterized by low productivity. On turret lathes, taper threading is performed using dies. If it is required to obtain a high-precision thread, then die heads with dies are used. various shapes. During the operation, the plates are automatically moved apart. Also used for tapered threads rollers, which allow thread rolling. Specially designed taps are used for internal tapered threads. Setting up a lathe for threading To perform turning threads with the specified parameters, it is necessary to fine-tune the machine. First of all, it is required to connect the rotation of the spindle with the movement of the caliper. The longitudinal feed per revolution of the spindle must be equal to the thread pitch. Screw-cutting lathes allow you to adjust the cutter feed due to the clutch gear wheels their pitch guitars and pitch boxes. Available a large number of clutch combinations of these wheels, which allows you to adjust the machine to any thread being cut. Threads are not cut on a CNC lathe - the main mistakes 1. does not cut at all (the start is on - the axes do not move - most likely there is no answer about the spindle speed from the sensor or the spindle rotation is not started) 2. does not fall into the turns (the presence of a large mechanical backlash, slippage of the encoder sensor or its kinematics) 3. cuts a thread with a pitch different from the specified one (check the threading cycle, the maximum threading feed rate, work in mm) General Checks - check the threading program, entry and exit according to the instruction manual (provide the text for analysis) - check the conformity of the material, cutter, spindle speed, feed, spindle range - (thread pitch, mm) * (number of spindle revolutions rpm) should not exceed top speed cutting feed along the axis (P1430) => reduce the spindle speed (the problem occurs when cutting coarse threads with a pitch greater than 8-10 mm) - check attachment electrical cables(connectors) and the cables themselves from the encoder to the CNC - check the fastening of the encoder on the headstock, encoder couplings, gears on the encoder shaft in the headstock -Check the parameter and the set value of the spindle encoder pulses per 1 revolution. P3720=4096 pulses * parameters are specified for CNC Fanuc 0i series Tapered pipe thread GOST 6211–81 is mainly used in joints where increased tightness of pipes is required at high liquid or gas pressures. According to international qualification, it has the designation BSPT (British Standard Pipe Thread). AT Russian Federation The main application of this pipe conical thread is found in the installation of water supply systems, heating, as well as in the installation of gas supply pipes. The profile of a conical pipe thread has an angle of 55°, its peaks and troughs are rounded. The pitch of this thread is expressed as the number of threads per inch. The taper angle on which the pipe taper thread is cut is 1°47′24″, which corresponds to a taper of 1:16. The external tapered pipe thread is conventionally designated by the letter R, and the internal tapered pipe thread by the letters Rc. The designation of the left taper thread is supplemented by the letters LH, and the right RH. Very often conical pipe thread called a cone. When choosing a thread-cutting tool, special attention should be paid to the marking of cutters - thread-cutting combs. They indicate the size and type of thread. Also do not confuse conical pipe BSPT thread and NPT conical pipe threads. NPT (National Pipe Thread) are designed for the manufacture of conical pipe threads (GOST 6111-52) and are used mainly in the USA, as well as in the installation of equipment manufactured in the USA at oil and gas processing plants in Russia. NPT threads have a different pitch and are not compatible with BSPT pipe threads. To see how to properly cut BSPT taper pipe threads with a screw clamp. It is possible to cut a thread on a pipe, in place, with the help of thread-cutting dies for pipe threads, as well as with the help of thread-cutting dies. Professional plumbers mainly use thread-cutting screws. Thread-cutting dies, unlike die cutters, are solid cutting tool. Klupp consists of a body - a head, four thread-cutting combs - cutters, an upper clamping washer and four fastening screws. Thread-cutting dies are marked with numbers from 1 to 4 and are installed in the head body in the seat with the corresponding designation. For cutting pipe threads with a die cutter, preliminary chamfering at the end of the pipe is not required, since the combs have a slight bevel for this and easily enter the pipe by removing excess metal. For threading with dies, it is necessary to have a flat end and a chamfer, otherwise the cutting edges can be ruined. For small volumes of pipe threading (renovation of an apartment, replacement of a pipe, installation of a heating radiator, etc.), a manual ratchet is used. Sometimes, for one-time threading, a gas pipe wrench is used. Capturing with a key can be carried out by the shank of the klupp - thread-cutting head. In a hard-to-reach place, with a head with a square shank, it will be difficult to perform work using a pipe wrench. Ratchet screws have a detachable handle for easy transportation and storage. When installing pipelines for heating, gas supply and water supply, also during repairs large volumes, it is best to cut the pipe thread with a screw driver using an electric drive. It is most commonly referred to as an electroclip or electric klupp. Cutting pipe threads with electric drive must be carried out according to the operating instructions, installed on the pipe using a clamp - clamp (read the instructions). If the pipe (its end) comes out of the wall, floor or ceiling, then it must be held with a pipe wrench or fixed with other pipe grips in such a way as to prevent it from turning during threading. This must be done both when using a manual ratchet and when using an electric drive. When cutting pipe threads, both with a manual ratchet and with an electric drive, a very high torque must be taken into account when rotating the threading die. You will not succeed in holding the pipe with your hands, no matter how hard you try. In such cases, it is better to install - fix the pipe using a pipe vise by placing them on a work bench or tripod folding workbenches with a pipe vise. You can watch videos in the section Videos. Prices, instructions and descriptions of devices can be found on the pages in the section Categories Curtains layout Kitchen Design Floor repair Wall repair Kitchen Appliances Kitchen care Furniture for kitchen Popular Ginger juice for weight loss The harm and benefits of flaxseed oil for women Flaxseed oil: medicinal properties, rules for taking Fennel: beneficial properties and effects on digestion Brown rice: glycemic index, calories, BJU norms and useful properties A decoction of lingonberry leaves, the benefits and harms Beans for weight loss: what are the benefits of bean diets? How to graft an apple tree in spring: timing and methods How to graft an adult apple tree Features of home cultivation of dracaena dragon Dragon tree at home The birthplace of the dracaena and what it brings to the house Dracaena meaning for the home Fitting © 2022 Design and interior of apartments