Profiles and thread sizes
(GOST 9484-81)The standard applies to trapezoidal threads and establishes the profiles and dimensions of its elements.
MAIN PROFILE
An example of a symbol for a trapezoidal single-start thread with a nominal diameter of 20 mm, a pitch of 4 mm and a tolerance field of an average diameter of 7e:
Tg 20 x 4 -7e
NOMINAL PROFILES
outdoor and internal thread
h 3 - profile height external thread; H 4 - the height of the profile of the internal thread; d 3 - inner diameter of the external thread; D 4 - outer diameter of the internal thread; R 1 - rounding radius at the top of the external thread; R 2 - twisting radius in the cavity of the external and internal threads; a c - clearance at the top of the thread.
DIAMETERS AND PITCHES
trapezoidal single-start thread according to GOST 24737-81
Preferred diameters and steps are specified in GOST 24738-81. Numeric values tolerances of diameters and steps - according to GOST 9562-81
DIAMETERS AND PITCHES
trapezoidal multi-start thread according to GOST 24739-81
Notes:
1. Steps in a box are preferred.
2. The steps indicated in brackets are not recommended when developing new designs.
3. Threads, in which the stroke value is marked with *, have a lead angle of more than 10 o. For these threads, the deviation of the profile shape must be taken into account during production.
4. In technically and economically justified cases, it is allowed to use other values of nominal thread diameters in accordance with GOST 24738-81.
5. When choosing thread diameters, the first row should be preferred to the second.
An example of a symbol for a trapezoidal multi-start thread with a nominal diameter of 20 mm, a stroke value of 8 mm, a pitch of 4 mm and a tolerance field of 8e:
Tg 20-8 (P4) - 8e
Same, left:
Tg 20-8 (P4) LH - 8e
The make-up length, if different from the thread length, is indicated in millimeters at the end of the thread designation, for example:
Tg 20-8 (P4) LH - 8e - 180
Numerical values of the lengths of make-up related to groups N and L - according to GOST 9562-81.
Landing in a threaded connection is indicated by a fraction
Tg 20-8 (P4) LH - 8H / 8e - 180
The numerical values of the tolerances of diameters d and D 1 - according to GOST 9562-81.
The numerical values of the tolerances of diameters d 2, d 3 and D 2 - according to GOST 24739-81.
Application trapezoidal thread
The trapezoidal thread of a screw is a lead thread that has a relatively great strength friction, it is self-braking. The advantage for lifting technologies is that it does not require additional fixation in the rest position.
Trapezoidal thread is used to convert rotary motion into linear motion and is used primarily for rectilinear motion. It also finds its use as a lead screw in lathes or as a drive thread for the screw press of tables or vehicle bridges.
Application examples for trapezoidal spindle threads:
Feed movement on machine tools (e.g. adjusting and lead screws);
- movement on the manipulator;
- traffic regulation lifting mechanisms and forklifts;
- movement of the shutter when locking injection molding machines;
- moving movement on assembly containers;
- vertical movement when working with a press.
Related Documents:
GOST 3469-91: Microscopes. Thread for lenses. Dimensions
GOST 4608-81: Metric thread. Interference landings
GOST 5359-77: Ocular thread for optical instruments. Profile and dimensions
GOST 6042-83: Round Edison thread. Profiles, dimensions and limit dimensions
GOST 6111-52: Conical inch thread with a profile angle of 60 degrees
GOST 6211-81: Conical pipe thread
GOST 6357-81: Cylindrical pipe thread
GOST 8762-75: Round thread with a diameter of 40 mm for gas masks and calibers for it. Main dimensions
GOST 9000-81: Metric thread for diameters less than 1 mm. Tolerances
GOST 9484-81: Trapezoidal thread. Profiles
GOST 9562-81: Trapezoidal single thread. Tolerances
GOST 9909-81: Conical thread of valves and cylinders for gases
GOST 10177-82: Thrust thread. Profile and main dimensions
GOST 11708-82: Thread. Terms and Definitions
GOST 11709-81: Metric thread for plastic parts
GOST 13535-87: Reinforced thrust thread 45 degrees
GOST 13536-68: Round thread for sanitary fittings. Profile, basic dimensions, tolerances
GOST 16093-2004: Metric thread. Tolerances. Landings with clearance
GOST 16967-81: Metric thread for instrumentation. Diameters and steps
GOST 24737-81: Trapezoidal single thread. Main dimensions
GOST 24739-81: Multi-start trapezoidal thread
GOST 25096-82: Thrust thread. Tolerances
GOST 25229-82: Metric conical thread
GOST 28487-90: Tapered tool joint thread for drill string elements. Profile. Dimensions. Tolerances
GOST 9484 - 81
Trapezoidal thread has a profile with an angle of 30°. thread pitch measured in millimeters.
Trapezoidal thread used in the nodes of mechanisms for converting rotational motion into translational, for example: lead screws of machine tools, power screws of presses, lifting screws, etc. Threads of this type can withstand significant loads.
Trapezoidal thread lettered Tr- English. trapezoidal
- Tr 28 × 5- diameter 28mm pitch 5mm
- Tr 28 × 5 LH- diameter 28mm pitch 5mm thread left
- Tr 20 × 8 (P4)- diameter 20 mm, pitch 4 mm and stroke 8 mm multi-start thread
- Tr 20 × 8 (P4) LH- diameter 20 mm, pitch 4 mm and stroke 8 mm multi-start thread left
d- outer diameter of the external thread (screw)
D– outer diameter of the inner thread (nut)
d2– average external thread diameter
D2– average diameter of internal thread
d1– internal diameter of external thread
D1– internal diameter of the internal thread
P- thread pitch
H is the height of the original triangle
H1– profile working height
| Trapezoidal thread | |||
| Thread diameters d | Step | ||
|---|---|---|---|
| Row 1 | Row 2 | ||
| 10 | 1.5; 2 | ||
| 11 | 2 ; 3 | ||
| 12 | 2; 3 | ||
| 14 | 2; 3 | ||
| 16 | 2; 4 | ||
| 18 | 2; 4 | ||
| 20 | 2; 4 | ||
| 22 | 3; 5 ; 8 | ||
| 24 | 3; 5 ; 8 | ||
| 26 | 3; 5 ; 8 | ||
| 28 | 3; 5 ; 8 | ||
| 30 | 3; 6 ; 10 | ||
| 32 | 3; 6 ; 10 | ||
| 34 | 3; 6 ; 10 | ||
| 36 | 3; 6 ; 10 | ||
| 38 | 3; 7 ; 10 | ||
| 40 | 3; 7 ; 10 | ||
| 42 | 3; 7 ; 10 | ||
| 44 | 3; 7 ; 12 | ||
| 46 | 3; 8 ; 12 | ||
| 48 | 3; 8 ; 12 | ||
| 50 | 3; 8 ; 12 | ||
| 52 | 3; 8 ; 12 | ||
| 55 | 3; 9 ; 14 | ||
| 60 | 3; 9 ; 14 | ||
| 65 | 4; 10 ; 16 | ||
| 70 | 4; 10 ; 16 | ||
| 75 | 4; 10 ; 16 | ||
| 80 | 4; 10 ; 16 | ||
| 85 | 4; 12 ; 18 | ||
| 90 | 4; 12 ; 18 | ||
| 95 | 4; 12 ; 18 | ||
| 100 | 4; 12 ; 20 | ||
| 110 | 4; 12 ; 20 | ||
| 1. When choosing a thread, priority is given to the first row. 2. The thread pitch in the highlighted color is preferred. |
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The operation of the drives of many machines, equipment and mechanisms is based on such a process as the transformation of rotational motion into translational motion. Drives operate according to this principle, for example. measuring machines and equipment, control systems for valves and valves, scanning tables, robots and machine tools.
In order to effectively convert the rotation of a certain part into the translational movement of another part, a screw-nut pair is most often used. Such transmissions are products that have a general machine-building application, and it should be noted that the performance, functionality and reliability of that equipment largely depend on how well they are designed and manufactured. constituent parts which they are.
Due to the fact that the screw-nut gears have an increased smoothness of engagement, they are almost completely silent during operation. Their design is relatively simple, and one of the undoubted advantages is that their use allows you to achieve a considerable gain in strength. By and large, the screw-nut transmission from a technical point of view is no different from a conventional threaded connection, however, since they are used to transmit movement, they are made in such a way that the friction force in the thread is minimal.
In principle, this can be achieved by using a rectangular thread, but it also has its drawbacks. For example, it cannot be cut on standard threading machines, and compared to trapezoidal threads, it has a much lower strength. These factors lead to the fact that rectangular threads are rarely used in screw-nut gears. They are most common trapezoidal thread, which has a large, medium and small pitch, as well as a persistent thread.
Most often in gears, a screw - nut can be found trapezoidal thread, which has average step. It, but with a small step, is used when it is necessary to provide a small movement, and with a large step - when the device is operated in difficult conditions. In addition, due to the profile features, trapezoidal thread can be successfully used in mechanisms requiring reverse movement. Such threads are single and multi-start, right and left.
Materials used in screw-nut transmissionThe main requirements for the materials used in screw-nut gears are wear resistance, strength and good machinability. As for those screws that are not hardened, they are made of steels A50, St50 and St45, and those that are hardened - from steels 40HG, 40X, U65, U10. Nuts are usually made of bronze BrOTsS-6-6-3 or BrOFU-1.
The thread profile is an isosceles trapezoid with an angle of 30° between the sides (Figure 3, c). Trapezoidal thread can be single and multi-start, right and left.
The diameters and steps of a single-start trapezoidal thread in the range of diameters from 12 to 50 mm are given in Table. 2. The same dimensions and number of starts for multi-start threads are given in Table. 3.
Thread designation examples:
trapezoidal rhno-leading with a nominal diameter of 36 mm and a pitch of 6 mm:
TgZbhb; the same, left-hand thread:
Tg 36x6 LH;
trapezoidal, three-start with a nominal diameter of 40 mm, a pitch of 3 mm and a stroke of 9 mm:
Tg 40 X 9 (RZ)
Examples of thread designation in the drawing are shown in fig. 5. at
Table 2. Diameters and pitches of a trapezoidal single-start thread according to GOST 24738 81, mm
| Diameter d | row | - | - | -" | - | - | ||||||
| - | - | - | - | - ■ | 30, | |||||||
| step | p | |||||||||||
| R* | 3;8 | 3;8 | 3;8 | 3;8 | 3; 10 | |||||||
| Diameter d | row | - | - | - - | ||||||||
| - | - | - | - | - | ||||||||
| step | R | 8, | ||||||||||
| R* | 3; 10 | 3;10 | 3;10 | 3;10 | 3;10 | 3;10 | 3;12 | 3;12 | 3;12 | 3; 12 |
Note: 1. When choosing a thread, the first row should be preferred to the second;
2. Preferred steps are marked with *.
Table 3. The main dimensions of the trapezoidal multi-start thread according to GOST 24739 81, mm
| d | thread pitch | Thread stroke with number of starts | ||||
| Row1 | Row 2 | R | R* | |||
| (8) | ||||||
| - | - | |||||
| - | - | |||||
| - | - | |||||
| ,-. - | - | (16) | (20) | |||
| - | - | |||||
| - | (20) | |||||
| _ | - | |||||
| - | (24) | |||||
| - | - | |||||
| - | (24) | |||||
| - | - | |||||
| - | (21) | (28) | ||||
| - | - | |||||
| _- | (28) | |||||
| ■ - | - | |||||
| - | (32) | |||||
| (24) | (36) | (48) | ||||
| - | - | |||||
| - | (32) | |||||
| - | (24) | (36) | (48) |
Note: A thread whose lead value is in brackets has a lead angle of more than 10°.
The carving is persistent.
The main purpose of the thread is to transfer an axial load in one direction by means of a screw, for example, in jacks, presses, etc. The thread profile is an unequal trapezoid (Fig. 3, d).
: > v Diameters and pitches of thrust threads in the range of diameters from 16 to 42 mm are given in Table. four.
Thread designation examples: "
thrust single-thread right with a diameter of 32 mm with a step of 6 mm:
the same, left-hand thread:
S32x6LH. In the drawing, the thread is indicated as shown in fig. 6.
Rice. 6
Table 4. Diameters and pitches of thrust threads according to GOST 10177 82, mm.
| Diameter d | Step | ||
| Row1 | Row 2 | R* | R |
| - | |||
| - | |||
| - | 3;8 | ||
| - | 3;8 | ||
| - | 3;8 | ||
| - | 3;8 | ||
| - | 3;10 | ||
| - | 3;10 | ||
| - | 3;10 | ||
| - | 3;10 | ||
| - | 3;10 | ||
| - | 3;10 |
Note^. When choosing thread diameters, the first row should be preferred to the second.
Steps that are preferred when developing new designs.
Pipe cylindrical thread.
This thread is used in cylindrical pipe connections and connections of an internal cylindrical thread with an external conical thread.
The profile (Fig. 3, b) and the main dimensions are established by GOST 6357 81. The values \u200b\u200bof the main dimensions of a cylindrical pipe thread are given in Table. 5.
The pipe thread designation (Fig. 7, a, b) consists of the letter G and the thread size in inches, for example:
This designation is conditional, because. indicates the diameter of not the thread, but the hole in the pipe (nominal bore DN at a certain wall thickness). The outer diameter of the pipe thread will be larger than indicated in the drawing. For example, the designation G1 corresponds pipe thread having an outer diameter d=33.25m designed for pipes with an internal diameter of 1" (25.4 mm).
Pipe cylindrical thread of the same diameter ( conditional pass DN) can be performed on pipes with different thickness walls and even on a solid rod.
Rice. 7. Conventions pipe cylindrical and conical threads: a) cylindrical pipe thread G 1 1/2;
b) thread of the same size internal, left; c) external pipe tapered thread; d) internal pipe conical
Table 5. The main dimensions of the cylindrical pipe thread
In mechanisms where it is necessary to convert rotation into translational motion, they use. In addition to its transformative function, this thread can withstand increased loads. This is a popular type of thread in important parts of mechanisms, machine tools. You can observe the principle of this thread when driving screws, when the rotation of the screw causes it to move in a linear direction. The force applied to transform the movement depends on the angle of the profile, the thread pitch and the material of the part.
The name of the carving comes from the resemblance to a trapezoid.
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The main characteristics of the trapezoidal thread
The trapezoid shape is formed by the angle of the thread profile. In this type, the profile angle can be in the range of 15 - 40 degrees.
In the working process, threads can cause excessive friction. This factor is affected by the profile angle, the type of lubricant and the material used. Radial gaps in trapezoidal threads can be identified by placing the thread in the middle of the diameter.
Trapezoidal thread is quite simple to manufacture. In most cases, the profile angle is set to 30 degrees. The quality of the thread depends largely on the accuracy of the workpiece used, as well as the material.
Trapezoidal thread cutting methods
The production of this type of thread can be divided into two categories - one cutter and three cutters.
As an example, consider the following designation: Tr 26 × 4 LH - trapezoidal thread, single start, with a diameter of 26 and a step of 4, left.
GOST 9484-81 is used as the main standard.
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