Top Chinese supplier of wind turbine founation anchor bolt.

EN14399 Hex Head Bolt Specification

EN14399 Hex Head Bolt

High-strength structural bolting assemblies for preloading

This standard on structural bolting reflects the situation in Europe where two technical solutions exist to achieve the necessary ductility of bolt/nut/washer assemblies. These solutions utilize different systems(HR and HV) of bolt/nut/washer assemblies. It is importance for the performance of the assembly to avoid mixing up the components of both systems. Therefore the bolts and nuts for both systems are standardized in one single part of this European Standard each and the marking of the components of the same system is uniform.

ENEN 14399-1 High Strength Structural Bolting Assemblies for Preloading

Longteng Steel is qualified to manufacture pre-load bolt assemblies as high strength structural bolt according to BS EN 14399-1:2015, thisHigh-strength structural bolting assemblies for preloading is classified in these ICS categories: High-strength structural bolting assemblies in accordance with EN 14399-2 to EN 14399-10 are designed to fulfil the requirements of this European Standard. High-strength structural bolting assemblies are suitable for preloading in accordance with EN 1090-2 in steel structures.
NOTE
According to this standard, high-strength structural bolting assemblies smaller than M12 are not designed to be preloaded. Longteng supplies structural hex head bolt in following sizes: M30, M33, M36, M39, M42, M45, M48, M52, M56, M60, M64, this type of hex head bolt is not suitable for railway fastener and weld treatment.

EN 14399-2 High-strength structural bolting assemblies for preloading Suitability for Preloading

This document on structural bolting reflects the situation in Europe where two technical solutions exist to achieve the necessary ductility of bolt/nut/washer(s) assemblies. These solutions consist of two different systems (HR and HV) of bolt/nut/washer assemblies (see Table 1). Both systems are well proven and it is the responsibility of the experts using structural bolting whether they use the one or the other system.
It is, however, important for the performance of the assembly to avoid mixing up the components of both systems. Therefore, bolts and nuts for both systems are standardized in one single part of this European
Standard each and the marking of the components of the same system is uniform.

BS EN 14399-3 High-strength structuralbolting assemblies for preloading HR system

EN 14399-4 PRE-LOAD BOLTING ASSEMBLIES HV Pre-Load Bolt Assemblies HV BS

Thread d M12 (M14)b M16 (M18)b M20
PC 1.75 2 2 2.5 2.5
b d 30 34 38 42 46
e 40 44 48 52
f 65
c max 0.8 0.8 0.8 0.8 0.8
min 0.4 0.4 0.4 0.4 0.4
da max 15.2 17.2 19.2 21.7 24.4
ds max 12.70 14.70 16.70 18.70 20.84
min 11.30 13.3 15.30 17.3 19.16
dw max g g g g g
min 20.1 22 24.9 27.7 29.5
e min 23.91 26.17 29.56 32.95 35.03
K non 7.5 8.8 10 11.5 12.5
max 7.95 9.25 10.75 12.4 13.40
min 7.05 8.35 9.25 10.6 11.60
Kw min 4.9 5.85 6.5 7.42 8.1
r min 1.2 1.2 1.2 1.5 1.5
S max 22 24 27 30 32
min 21.16 23.16 26.16 29.16 31
  Bolt/nut/washer assembly System HR Bolt/nut/washer assembly System HV
General Requirements EN 14399-1
Bolt/nut assembly EN 14399-3 EN 14399-4
Marking HR HV
Property classes 8.8/8 10.9/10 10.9/10
Washer(s) EN 14399-5 or EN 14399-6 EN 14399-5 or EN 14399-6
Marking H H
Suitability test for preloading EN 14399-2 EN 14399-2

EN 14399-5:2015 Pre-Load Bolt Assemblies Plain Washers

This European Standard specifies, together with EN 14399-1 and EN 14399-2 , hardened and tempered plain washers intended for bolting assemblies with large series hexagon high-strength structural bolts and nuts with threads from M12 to M36 inclusive. Washers according to this standard can be applied under the nut only. Washers according to this standard are not intended to be used in direct contact with oversized or slotted holes.

DIN EN 14399-6 High-strength structural bolting assemblies for preloading – Part 6: Plain Chamfered Washers

Nominal size
(nominal thread diameter of associated bolt)
12 16 20 22 24 27 30 36
1 min >13 17 21 23 25 28 31 37
max 13.27 17.27 21.33 23.33 25.33 28.52 31.62 37.62
d2 min 23.48 29.48 36.38 38.38 43.38 49.0 54.80 64.80
max 24 30 37 39 44 50 56 66
h nom 3 4 4 4 4 5 5 6
min 2.7 3.7 3.7 3.7 3.7 4.4 4.4 5.4
max 3.3 4.3 4.3 4.3 4.3 5.6 5.6 6.6
e nom=min 0.5 0.75 0.75 0.75 0.75 1 1 1.25
max 1 1.5 1.5 1.5 1.5 2.0 2.0 2.5
c min 1.6 1.6 2.0 2.0 2.0 2.5 2.5 2.5
max 1.9 1.9 2.5 2.5 2.5 3.0 3.0 3.0

Longteng High Tensile Strength Rock Bolt For Mining Roadway Safety

On November 3, the 2020 National Science and Technology Award Conference was held in the Great Hall of the People in Beijing. A total of 58 achievements won the second prize of the National Technological Invention Award, including anyang Longteng Heat Treatment Materials Co., LTD. ‘s coal mine roadway impact resistance prestressed support key technology project. On November 11, the reporter came to the Anyang Longteng heat treatment material Co., LTD., located in the North Meng street of Yindu District.

How does Anchor Rock Bolt of Longteng Help Coal Mine Industry

In the process of coal mining, coal mine roadway is the channel between the surface and the ore body, bearing the functions of ventilation, drainage, mining, pedestrian and so on. High strength rock bolt is the key to ensure the safety of coal mining. It is not only the transport channel to ensure the normal mining of coal mine, but also the life channel to maintain the safety of the operation personnel. “In order to ensure the safe operation of underground structure construction in coal mine, the mining side must take safety measures such as retaining and reinforcing the side wall of coal mine roadway, which is known as support technology in the mining field.

With the increase of the depth and intensity of coal mining, the traditional support technology can no longer meet the needs of maintaining the safe operation of the roadway, resulting in metal support damage, roof collapse and other phenomena, posing a threat to the safety of the coal mine. The company’s deputy general manager Fu Guangqing introduced, in order to reduce the maintenance cost of coal mine roadway, improve support technology, Anyang Longteng Heat treatment Materials Co., Ltd. in the national “863” program and the national Natural Science Foundation and other projects funded, coal mine roadway anti-impact prestressed support key technology research.

Anchor Rock Bolt Development in Longteng

In coal mine roadway, the anchor rock bolt is one of the most important materials in a supporting role, Anyang Longteng heat treatment material co., LTD., a new heat treatment process, greatly improving the strength and impact toughness of ordinary steel anchor, to solve the ordinary rock bolt hit problem of easy break by high strength, and greatly reduces the maintenance cost of roadway. At present, the rock bolt material made by the new technology has been popularized and applied in 18 mining areas in Henan, Shandong, Shanxi and other provinces, which provides technical guarantee for mining deep and complex coal resources.

Reporter walked into the production workshop. Next to the long automated high strength steel rod production line, a special working area is divided at intervals. Different equipment is placed in the working area for heat treatment, machining and so on. At one table, two skilled workers are recording their observations. Go to the end of the production line, in the storage area of rock bolts, rock bolts are stacked orderly after packaging.

It is conceivable that these rock bolts will be used to support the roadway after being transported to various mining areas. Anyang Longteng Heat treatment material Co., Ltd. by virtue of advanced technology, will make important contributions to the safe operation of coal mine underground structure construction and the healthy development of coal mining industry.

In the workshop of Anyang Longteng Heat treatment Materials Co., LTD., automated production lines, industrial robots can be seen everywhere, with these advanced process equipment, without manpower can ensure the efficient production of products.

Attention to technology research and development is anyang Longteng heat treatment materials Co., LTD. At present, the company has in henan province enterprise technology center construction, high strength steel engineering technology research center, Anyang city, Henan province heat treatment, high strength high performance steel laboratory of new materials research and testing, based on these research institutions, technical personnel to carry out independent research and development activities actively, has applied for more than 10 invention patents, utility model patents. Feng Bo, head of the company, said, “Because of our emphasis on technological innovation and independent research and development,

Anyang Longteng Heat Treatment Materials Co., Ltd. has achieved one brilliant achievement after another. The second prize of The State Technological Invention Award is a recognition of the efforts made by all our employees. We will take this award as an opportunity to continue to tackle key problems and scale new heights of science and technology through independent research and development to promote high-quality development of the enterprise.”

Grade 10.9 Stud Bolt and Hex Bolt for Sale

Longteng produces high strength 10.9 stud bolt and hex head bolt for customers, 10.9 stud and hex head bolt are available in large dimensions at Longteng, usually M24-M80 which are made of carbon and alloy steels. Bolt with no head and thread at both ends called stud bolt, There are also all thread stud bolt.

Here are black oil treated M24 stud bolt and M36 hex bolt packaged in wooden boxes. If you are interested, please feel free to contact info@high-strength-steel.com now!

Here are packaged M24*300 stud bolt packaged for delivery, M36*350 half three hex bolt for customers abroad.

M56 Stud Bolts Production Finished for Customer

Great news, Longteng has finished production of shipbuilding stud bolts for exporting, this is an M56 Stud Bolt order for shipbuilding purposes, if you need to buy high-quality stud bolt, contact us now!

DIN EN ISO 4014 / 4017 M-27 to M-72 Carbon steel / Alloy steel Ship building, ship yard, decks

We manufacture high tensile quality stud bolts and hex head bolt used in ship building industry, from zinc plated bolts & nuts to manufacturing good quality anti-corrosion steel bolts & nuts, Longteng has the expertise to supply most reliable fasteners to this industry and other industries.

Anti-corrosion steel and special marine grade stud bolts & nuts are used in the ship building industry which are being manufactured by Longteng with the rich experience in producing big bolt with high tensile strength for wind towers . These stud bolt and hex bolts & nuts used in the ship yards and ships are of world class quality in anti-corrosion steel and electroplated steel grades.

Welcome to Longteng at 21st Suzhou Fasteners and Technology Exhibition

Great news, The 21st Suzhou Fasteners and Technology Exhibition has begun, time is October 27-29, 2021, welcome to visit Anyang Longteng at Suzhou International Expo Center.

Anyang Longteng annual production of high-strength and high-performance heat-treated steel 150,000 tons,  has passed EN 10204 Type 3.1 Inspection Certificate for anchor bolt, stud bolt, structural tie rod products.

Main products are wind turbine foundation prestress anchor bolt, anchor plate, turbine bolt, high strength heat-treated structural tie rod, super-high-strength heat-treated rock bolt rebar, prestress heat-treated concrete rebars and hot-rolled seamless steel pipes, widely applied in Bridge, highway, railway, tunnel, new energy, mining, steel structure, rebar concrete structure, etc.

Anyang Longteng Heat Treatment Material Co., Ltd was established on 19th Jan. 2005, with more than 147,890,000 RMB registered capital, the total area of 300 acres, building area of 100,000 square meters, 500 employees.

Visit Anyang Longteng at 2021 Beijing Wind Energy Exhibition

Anyang Longteng Heat Treatment Material Co., Ltd. (formerly Anyang Longteng Special Steel Manufacturing Co., Ltd.) was established on January 19, 2005, with a registered capital of 147.89 million yuan, covering an area of more than 300 acres, a building area of 100,000 square meters, and more than 500 employees.

Welcome to Anyang Longteng at Beijing Wind Energy Exhibition, we are here to introduce to you high tensile steel rod products manufactured for onshore wind anchor cage foundation, wind turbine bolt, wind tower bolt.

The main products are: high-strength stud bolts, wind energy anchor bolts, blade bolts, high-strength hexagonal head bolts, embedded sleeves and other high-strength fasteners.


EN 10204 Type 3.1 Inspection Certificate for Longteng Bolt Products

Round Bar - Anchor Bolt Raw Material

Difference Between EN 10204 Type 3.1 And Type 3.2

Designation of the document type
EN 10204  Reference English version German version French version Document content Document
validated by
Type 3.1 Inspection certificate 3.1 Abnahmeprüf-
zeugnisse 3.1
Certificat de réception 3.1 Statement of compliance with the order, with indication of results of specific inspection The manufacturer`s authorized inspection representative, independent of the manufacturing department
Type 3.2 Inspection certificate 3.2 Abnahmeprüf-
zeugnisse 3.2
Certificat de réception 3.2 Statement of compliance with the order, with indication of results of specific inspection The manufacturer`s authorized inspection representative independent of the manufacturing department and either the purchaser`s authorized inspection representative or the inspector designated by the official regulations

EN 10201 Type 3.1 Introduction

The EN 10204 Type 3.1 Inspection Certificate are actual test results from the material in the lot from which the steel products have been supplied (formally referred to as “specific testing”). A 3.1 Inspection Certificate is endorsed only by the manufacturer’s own representative who has to be independent from the manufacturing process, such as the Quality department or a test house manager/supervisor.

Longteng is qualified to provide EN 10204 Type 3.1 Inspection Certificate as test results from the material in the lot from which the steel products have been supplied, this Inspection Certificate is endorsed only Longeteng who has to be independent from the manufacturing process, such as the Quality department or a test house manager/supervisor.

Why Choose Manufacturer with EN10204 Type 3.1 Certificate

If a metal material factory has passed the ISO 9001 certificate issued by an EU-authorized certification body, and the metal material meets the European material specifications, the factory can issue an EN10204-3.1 material certificate to its customers.
It’s a very reliable decision for Customers who need large size stud bolt or hex bolt to choose Longteng as the supplier, for there is a guarantee of steel rod raw materials and product quality according to its strict manufacturing process and tests.

Round Bar - Anchor Bolt Raw Material

With Longteng Applied Technologies is familiar with the requirements of a Type 3.1 inspection certificate and we understand its importance to our customers. While the 3.2 certificate is rare due to the higher cost, it provides independent assurance of a material’s properties. If you need more help understanding your 3.1 certificate, or simply need help retrieving a certification for a component you’ve purchased previously.

Anchor Cage Foundation Construction Process for Wind Mill Project

Anchor Cage Foundation Project

In recent years, wind power has been increasing in both the number and scale in China, however, most wind generator mainly used in wind farms adopt anchor cage foundation, main function of anchor plate is to connect the bolt and concrete structure, the upper structure of main parts, so the anchor plate is responsible for the wind machine structure are all load to the anchor cage foundation, ensure its structure with high stability. However, the foundation anchor plate is not deeply buried, the wall of the foundation anchor plate has few pores, the amount of internal reinforcement is small, there is no fixed pin, and the foundation reinforcement is not welded together, resulting in poor durability, load resistance and integrity of the foundation ring. The prestressed anchor bolt foundation is mainly distributed in the whole foundation by anchor bolt. The steel bar and anchor bolt adopt alternate frame, which has a high integrity. In addition, a high-strength tensioning tool is used to apply pretension on the anchor bolt, which enhances its durability and load-resisting ability.

Wind Foundation Anchor Cage
Wind Foundation Anchor Cage

The wind mill foundation used in a wind farm is a plate independent form, with a diameter length of 18 m and a buried depth of 3 m. The wind mill anchor cage foundation mainly applies the pre-stressed anchor and bolt technology and is installed in the construction site. The installation of high strength anchor bolts and anchor plate is strictly required. After secondary grouting, the flatness error of anchor plate should be controlled within 2 mm.

The pre-stressed anchor bolt foundation construction technology is used in many project, and the process is mainly as follows: pre-construction work, selection of embedded parts, setting and adjusting lower anchor plate, matching fixed anchor bolt and upper anchor plate, setting common anchor bolt, reasonably combining and inspecting anchor bolt, and then starting the construction of reinforcement and concrete.

Anchor Bolt Assembly Test and Standard

Test items Type test Factory inspection Standard method
Chemical composition 20MnTiB 、42CrMoA、40CrNiMoA、30CrMnSiA GB/T3077 — 1999
35VB GB/T1231-2006 Appendix A
45、35 GB/T699 — 1999
Tolerance class Bolts, screws, studs GB/T3103.1 — 2002
Nut GB/T3103.1 — 2002
washer GB/T3103.3 — 2000
Mechanical properties Bolts, screws, studs GB/T 3098.1 — 2010
Nut GB/T 3098.2 — 2000
Dacromet coating thickness   GB/T 18684 — 2002
Salt spray test   GB/T18684 — 2002
Ammonia drop test   GB/T18684 — 2002
Adhesion test   GB/T18684 — 2002
Surface defects Bolts, screws, studs GB / T5779.1 – 2000 GB / T5779.3 – 2000
Nut GB / T5779.2 – 2000

Pre-construction of Anchor Cage Foundation

  • Determine the number of anchor bolts, check the appearance of upper and lower anchor plates, anchor bolts and thread, and clean up non-conforming materials.
  • The anchor bolt assembly shall be delivered to the site by loading truck and protected by cork pad to prevent deformation of the upper and lower anchor plate and damage to the original state of screw thread.
  • The embedded parts shall be retained, and the embedded parts of the anchor plate shall be set according to the standard of the foundation design drawing of the prestressed anchor bolt, and the quantity, size and position of the embedded parts shall be adjusted.

Set Down Anchor Plate and Adjust Its Flatness

  1. The lower anchor plate is mainly raised by the crane, and then moved to the position of 300mm above the embedded parts to stop the movement. First, the bolts of the lower anchor plate are inserted into the corresponding screw hole, and the bolts from inside to outside are exactly corresponding to the embedded parts. At this time, the crane lowers the lower anchor plate to the top of the embedded parts.
  2. The center of the lower anchor plate is matched with the foundation center. The bolts of the lower anchor plate and embedded parts are tightly welded together, and the height is controlled at ≥ 6mm.
  3. The plane of the lower anchor plate tends to be flat. By rotating the supporting anchor bolts, the lower anchor plate meets the height requirements of the drawing design, and its levelness is controlled at ≤ 3mm. Figure 1 shows setting the lower anchor plate and adjusting its flatness.
Auto Pouring Concrete to Anchor Cage Foundation

The Positioning Anchor Bolt and Upper Anchor Plate Are Paired Together

The upper anchor plate is hoisted by the crane, and the upper positioning anchor bolts are evenly matched from top to bottom on all bolt holes of the upper anchor plate, and then the anchor bolts are firmly fixed with temporary nuts. The anchor bolts are fixed with black nuts, and the outside of the anchor bolts is wrapped with PVC sleeves Tube, plus a heat-shrinkable tube sleeve. Nylon adjusting nut is used to fix the head of the anchor bolt.

The Upper and Lower Anchor Plates Are Precisely Matched

The upper anchor plate and the positioning anchor bolt are slowly raised and fixed directly above the lower anchor plate. The positioning anchor bolt and the matching bolt hole of the lower anchor plate are connected together. A gasket is placed below the lower anchor plate to fix the black nut, and the fixed torque is controlled at 300 N·m. FIG. 2 shows the exact matching of the upper and lower anchor plates.

Installation Work of Other Anchor Bolt Parts

After positioning anchor is fixed, the fixed anchor bolt is mainly based on the principles of diagonal sequence, ordinary bolt head through the first anchor plate, the other part through the anchor plate, based on the same principle, the other anchor fixed well, the bottom of the anchor bolt nut is fixed, with black coated PVC casing, and then add a layer of heat shrinkable tube, each floor installation gaskets, with black nut is fixed, the fixed torque control at 300 n. m.

Adjust and Check Anchor Bolt Assembly

  1. Adjust the concentricity of the upper and lower anchor plates. The Angle of the four bolts was measured by theodolite as 90°, which was taken as a reference. A pile was installed on the ground outside the wind power foundation at an interval of 90°, and was connected between the upper anchor plate and the pile with drag rope. The center line of the anchor bolt hole of the upper and lower anchor plate was regarded as a reference for adjusting the concentricity, and the standard length was within 3 mm.
  2. Adjust the level of anchor plate. The leveler is used to measure the levelness of the upper anchor plate. When the levelness does not meet the standard, the upper anchor plate shall be raised by jack and the nylon nut shall be further fixed to make the levelness meet the requirements.
  3. The excess length of the upper anchor plate at the anchor bolt head shall be controlled at L Within ± 1.5 mm.
  4. Heat the heat shrinkable tube, place the plug between the anchor bolt and the upper anchor plate anchor bolt hole, and fix the anchor bolt in the center of the anchor bolt hole.
Erecting Formwork and Pouring Concrete
Erecting Formwork and Pouring Concrete

Strapping Steel Rebars, Erecting Formwork and Pouring Concrete

  1. After finishing the adjustment work, the top and upper anchor plate of the steel bar are welded together through 4 steel bar anchor and bolt assemblies, which are strengthened according to the cross shape. The bottom and the embedded parts of the anchor cage foundation are welded together, and the cross spot welding of the 4 steel bars is done to strengthen the firmness of the anchor and bolt assemblies.
  2. Before concrete pouring, the upper anchor plate shall be tested for its levelness for the second time, and the levelness shall be no more than 2mm.
  3. When pouring concrete, the upper anchor plate and anchor bolt are sealed with plastic to prevent contamination.

Reliable Mining Roof Bolts Support for Your Mining Project

Mining Roof Bolts

Mining Roof Bolts Case Introduction

The mine engineering design annual production capacity is 1.8 million Ton, due to the complex geological structure in the minefield. In the design and construction of mining roof bolts support, support forms and parameters are selected based on experience or engineering analogy, so there are some problems, such as difficult roadway maintenance, low coal production rate and tight mining replacement. In order to solve these problems, take project mine roadway as the engineering background to carry out solutions based on the analysis of roadway deformation mechanism and support technical effect. The successful application of mining roof bolting, netting and cable combined support has important significance and practical application value for improving coal production rate, reducing support cost of mining roadway, and realizing high yield and high efficiency in mining roadway roof support.

In the construction and production of high-efficiency mines, the common mining roof bolts support has not been able to meet the requirements of mechanized large-scale production due to the fast construction speed. In order to solve the contradiction between the rapid excavation and the lagging of support, the combined support of high strength anchor bolt and anchor cable has been popularized and applied as the main support method. Mine roadway and semi-coal rock roadway are mainly mining rock bolted-net shotcrete, it is mainly bolted-net and anchor rock bolt + steel belt (or reinforced beam) support, general chamber also adopts rock bolt-net shotcrete + anchor cable support, only in special places (such as large ground pressure roof broken area) shed support. High strength roof bolt and cable combined support has the advantages of fast supporting speed, good effect and low cost.

Dimensions and Allowable Deviations of Hot-rolled Roof Bolts

Size Inner diameter Rib Height Rib Width Out of roundness Rib space
nominal size  allowable deviations nominal size  allowable deviations nominal size allowable deviations
Φ16 16 +0.5
+0.1
1.5 +0.4 1.0 ≤0.4 11.5 +0.5
Φ18 18 +0.5
+0.1
1.5 +0.4 1.3 ≤0.4 13.3 +0.5
Φ20 20 +0.5
+0.1
1.5 +0.4 1.3 ≤0.4 13.3 +0.5
Φ22 22 +0.5
-0.4
0.8 +0.3
-0.2
1.1 ≤0.4 12 +0.8

Main Factors Affecting Mining Roof Bolts Support

  1. The design method of mining roof bolts support is not scientific. Although its specification for coal roadway has been formulated, engineering analogy method is adopted in most of the design, and the support form and parameters are not reasonably determined. It is possible that the support strength is too much higher than the required level, the roof support structure cost is too much, for mining roof bolts are wasted. In soft, and other special geological conditions under the support strength may be insufficient, there is a possibility of danger, as roof collapse and other accidents may occur.
  2. The supporting material quality of mining roof bolt fails to reach the requirement. There might be various reasons, such as steel quality, thread quality of processing, resin coil quality are directly affected by the quality of support.
  3. The monitoring instrument and technology of mining roof bolts have high accuracy. The accuracy and practicability of the commonly used instruments are not perfect, which can not reflect the effect of bolt support completely.
  4. Under the existing technical conditions, the construction factor is the key link that directly affects the reliability of mining roof bolts support. The construction personnel does not have enough knowledge of the rock bolting support theory, or skills to install rock bolt properly, and the installation and operation quality management of the rock bolting cannot meet the design requirements. Such as sometimes only do the mining roof support and ignore the roadway side and floor, or some workers are not skilled enough and lacks sense of responsibility resulting in bolt and cable support strength reduction.
  5. In the construction of roadway uneven rock bolt anchor plate is not close to the rock surface, resulting in the failure of the mining rock bolt installed with no prestress. Different machines, tools and techniques used in the installation process lead to different pre-tensioning forces and different growth of support resistance after the installation of adjacent mining roof bolts, which will affect the support effect.

Mining Construction of Roof bolts

Rock Bolt for Tunnel Roof Support

During the installation of the resin bolt, the bolt must be pushed to the bottom of the hole to achieve the anchoring force. The agitator should be gently pushed vigorously, in order to quickly coagulant and resin stir evenly. When installing the nut of bolt support plate, the resin should reach a certain strength. The curing rate of resin and the growth rate of strength are accelerated with the increase in temperature. Practice shows that when the construction temperature is above 5 ℃, the supporting plate can be installed within minutes after mixing.

When the construction site temperature is below 5 ℃, the installation time should be postponed appropriately. The construction sequence is as follows: firstly construct the middle bolt, then construct the side bolt, dig a row spacing for each row, install a row of bolts, and make the jacking bolt and the side bolt work in parallel as far as possible.

  • According to the design requirements to excavate the roadway section, and then laid roof net, steel belt.
  • Use a single bolt drill to push the anchor hole to the design depth, place resin coil inside the hole, super-fast coil at the bottom of the hole, medium-fast coil at the outer part of the hole, and then use the assembled bolt to send the coil to the bottom of the manhole.
  • Lay the side net, set up the steel bar and the tray, tighten the nut with the plank hand, that is, complete the installation of a side bolt.

How to Install Roof bolts for Underground Mining

Construction tips for roof bolts install: from top to bottom, from back to front in turn.

  1. Clean the coal side to make it reach the design section size, and then determine the anchor hole position according to the design requirements.
  2. With the first hit the upper of the coal electric drill for bolt holes to design depth pack resin cartridge, the drill with connector and bolt, and start the drill, stirring side, until the bolt head to the bottom of the manhole, time is about 20 a 30 s, and then stop waiting for medicine curing, constraints, 30 s and then start the drill to tighten the nut, bolt installation. Lay the side net, set up the steel bar and the tray, tighten the nut with the plank hand, which is, complete the installation of a side bolt.

Anchor Cable Construction Tips

  1. Cut the steel hinge line according to the design length, remove rust and sludge (especially the internal anchoring section), install burr and retaining ring in the anchoring head section.
  2. Fix anchor cable hole position according to design requirement, use single anchor bolt drill, drill pipe and rotary bit to drill anchor cable hole to design depth.
  3. To hole placed resin cartridge, cartridge of super fast on the hole bottom, the medium cartridge placed outside the hole section, and then gently with the prepared steel strand pushing resin cartridge to the bottom of the hole, with stirring connector connect steel strand and drill, start the drill, stirring edge ahead, until to push resin cartridge to the bottom of the hole, such as back drill after 2 min, mixing connector, complete anchor cable anchorage.
  4. After resin anchoring and curing for 30 minutes, install jostles, trays and locks, and make them cling to the roof, hang tensioning, open the pump for tensioning, and observe the blasphemies of the pressure gauge, until pretension is designed, tension is stopped, jack is removed, and anchor cable is installed.

Test shows that rock bolt for mining roof with low initial anchor force cannot effectively control the displacement and deformation of surrounding rock. After the deformation, it only relies on the bracket of the net, beam and steel belt to prevent it from falling, which will increase the support cost. So by simply increasing the strength of roof bolt rebar, and neglecting to increase the primary anchor force, the strength of rock bolt rebar cannot be effectively exerted. Strictly control the mixing, solidification and waiting time of anchoring agent to ensure that the anchoring force meets the requirements of setting a standard, and the roles of composite beams and reinforced effect.

To make the anchorage rock bearing structure form as one structure, improves strata bearing capacity through changing the lower strata stress, effectively reduce the deformation of surrounding rock of roadway surrounding rock control early abscission layer, to improve the reliability of roadway roof support. After roadway excavation, the failure of surrounding rock gradually develops from the bottom to the roof, which shows that strengthening the support of the side walls plays an important role in the stability of the mining roof support. Prestressed rock bolt can effectively control the displacement of coal roof and the side walls. The higher initial anchor force of the rock bolt is main force to form “rigid” beam and “rigid” wall structure.

 

Rock Anchor Bolt Design and Production Line Equipments

Rock Anchor Bolt after Threading

Right-handed rock anchor bolt adopts the design of right spiral rib and one-way right screw thread, reinforced pitch and anchor bolt connection internal thread can be directly and effectively coordinated, it has the following advantages: simple connection and anchoring, strong adhesion, safety and reliability, etc. It is mainly used in underground rail track support engineering of coal mine, for ensuring smooth underground railway safety and coal mine construction industry. Except for low strength and poor safety of domestic old type rock anchor bolt, there are also higher strength and high tensile rock anchor bolt being developed.

Rock Anchor Bolt Production Line – Equipment Introduction

Here is a sample of small steel mill for rock anchor bolt production. Steel Mill adopts all rolling system, the air and gas – double heat furnace, use steel billet as raw material, with alternate arrangement of 6 roughing mills, and finishing mill group in all 6 high rigidity of short stress mills , and setting controlled cooling after rolling equipment, which is 120 m x 10 m step cooling equipment.

High Strength Rock Anchor Bolt Production

Here are list of difficulties and aspects in combination equipments in small steel mills for anchor bolt production:

  1. High strength rock anchor bolt steel has high-performance requirements. The raw material composition of steel rebar cannot reach the required yield strength and elongation, so it needs to be controlled in rolling process and heat treatment after rolling. The finished rock anchor bolt yield strength requires high carbon content, but it will lead to poor elongation. There are clear requirements for elongation in the standard, which requires post-rolling heat treatment. However, there is no post-rolling heat treatment equipment in small steel mills.
  2. The difficulty of rolling process development lies in the fact that steel rebar produced needs to be directly fitted with nuts, which means its size has to meet the deviation of standard requirements, and the threads on both sides should be exactly on the same spiral line. Therefore, groove width, expansion angle and radius of the base circle should be reasonable in the design of the threading process, and the cross rib spacing and included angle of the finished hole should be precise in both the design and processing.
  3. The middle and finishing mill groups without vertical roll rolling of continuous rolling production line, which requires torsion rolling; The second flow balance of rolled pieces cannot be controlled accurately, and the end – end difference will occur. The steelhead and tail have an extra part basically, which influence finished production rate.
  4. High processing precision is required for of finished rock anchor bolt products rolling groove; consistent transverse rib spacing between upper and lower rollers; consistent transverse rib spacing between the same roll; the actual pitch spacing of rolled products shall be consistent with the target value, and the design value of the transverse rib spacing shall be taken into account of impacting of sliding forward, cold shrinkage and others.
  5. Rolling mill, reducer quality ensures the upper and lower roll speed synchronization, no axial movement for rolling mill.

In order to solve the above problems completely before test run production of rock anchor bolt rebar, marking threads similar to right-handed rock anchor bolt steel transverse ribs were selected for test verification during production, so as to shorten the process development period and improve the success rate.

Design of Rock Anchor Bolt

  • According to the use characteristics and dimensions of high strength rock anchor bolt steel, the design ideas of finished pass and finished front pass are determined:
  • The finished product’s inner diameter height and width of free expansion surface shall meet the standard requirements; transverse rib filling degree is guaranteed on the premise, width of free expansion surface is as close as possible to the lower limit of the standard;
  • Accurately measure the influence of forwarding sliding and cold shrinkage of Kl under certain conditions, and make corresponding data compensation during design, control the spacing deviation of transverse ribs within 0.2mm after the steel bar is cooled;
  • Determine the diameter of Kl rolls of different specifications and the number of transverse ribs processed according to the front slip value, outlet speed of rolled pieces, the distance between transverse ribs and adjustment form to ensure the alignment effect and accuracy;
  • Adjust the angle of the axis of the transverse rib, which can directly fit with the nut of the same specification under the condition of the horizontal rib alignment.

Rock Anchor Bolt Grades and Mechanical Properties

Grade MG335 Yield Strength(MPa) Tensile Strength(MPa) Elongation(%)
Not Less Than
MG335 335 490 20
MG400 400 570 20
MG500 500 630 18
MG600 600 800 18

The proper calculation method of cross-rib alignment is determined through calculation and selection, so as the relationship between cross-rib phase error distance and adjustment parameters, the accurate rib alignment is realized through empirical data compensation, and the accuracy of roll turning and cross-rib machining is improved to create conditions for the successful manufacture of the high-strength rock anchor bolt.

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