Do You Know about Stud Bolts?

Do you know about stud bolts?

Stud bolts (Stud), also called stud screws or threaded rod. Used for the fixed connection function of connecting machinery, stud bolts have threads on both ends, and the screw in the middle can be thick or thin. Generally used in mining machinery, bridges, cars, motorcycles, boiler steel structures, tower cranes, large-span steel structures and large buildings.

Basic introduction

Bolts specifically refer to screws with larger diameters, and can also be headless, such as stud bolts. Generally, they are not called "stud bolts" but "stud studs". The most common form of stud studs is that they have threads on both ends and a bare rod in the middle.

The most typical use: anchor bolts, or places similar to anchor bolts, thicker connections, when ordinary bolts cannot be used.

Specifications

The thread specification d=M12, nominal length L=80mm, and performance grade 4.8 equal length stud bolts are fully marked as: GB 901 M12×80

Main  application

• 1. Used in large equipment where accessories need to be installed, such as sight glasses, mechanical seal seats, reducer racks, etc. At this time, stud bolts are used. One end is screwed into the main body, and the other end is nutted after the accessories are installed. Since the accessories are often disassembled, the threads will be worn or damaged, and it is very convenient to replace them with stud bolts.

• 2. Stud bolts are used when the thickness of the connecting body is very large and the bolt length is very long.

• 3. Used to connect thick plates and places where it is inconvenient to use hexagonal bolts, such as concrete roof trusses, roof beam suspension monorail beam suspension parts, etc.

Purpose of anti-loosening

In actual work, external loads such as vibration, change, and high-temperature creep of materials will cause friction to decrease. The positive pressure in the thread pair disappears at a certain moment, and the friction is zero, which makes the threaded connection loose. If it is repeatedly used, the threaded connection will loosen and fail. Therefore, anti-loosening must be carried out, otherwise it will affect normal work and cause accidents.

Surface treatment

Stud bolts generally need to undergo surface treatment. There are many types of bolt surface treatments. Commonly used ones include electroplating, blackening, oxidation, phosphating, and non-electrolytic zinc sheet coating. However, electroplated fasteners account for a large proportion of the actual use of fasteners. Especially in the automotive, tractor, home appliances, instrumentation, aerospace, communications and other industries and fields, it is more widely used.

However, for threaded fasteners, not only a certain anti-corrosion ability is required during use, but also the interchangeability of the thread must be guaranteed, which can also be called screwability here. In order to simultaneously meet the dual use performance of "anti-corrosion" and "interchangeability" required for threaded fasteners in use, it is very necessary to formulate a special electroplating layer standard.

GB/T5267.1-2002 [Threaded fasteners electroplating] is one of the national standards for "fastener surface treatment" series, which includes: GB/T5267.1-2002 [Fasteners electroplating]; GB/T5267.2-2002 [Fasteners non-electrolytic zinc flake coating]. This standard is equivalent to the international standard ISO4042; 1999 [Threaded fasteners electroplating]. This standard replaces GB/T5267-1985 [Threaded fasteners electroplating] standard.

Basic knowledge and maintenance

The production of stud bolts requires fixed equipment and machine processing. Of course, the processing procedure is relatively simple. The main processes are as follows: First, it is necessary to pull the material. Pulling the material is to use a puller to straighten the distorted material. After this process, the next process can be carried out. The next process is to use a cutting machine to cut the straightened long material into the length required by the customer according to the customer's requirements. This completes the second process. The third process is to put the cut short material on the thread rolling machine to roll out the thread; here the ordinary stud bolts are processed. Of course, if other requirements are required, other processes are required.

Generally known bolts refer to screws with larger diameters. According to this statement, screws are much smaller in diameter than bolts. Stud bolts have no heads, and some are called studs. Both ends of the stud bolts are threaded, and the middle does not contain threads. The middle is a bare rod.

Stud bolts are used on large equipment such as reducer racks. In actual use, the external load will vibrate and the influence of temperature will cause the friction to decrease. Over time, the threaded connection will loosen and fail. Therefore, it is necessary to do a good job of maintaining the stud bolts in normal times.

Stud bolts or anchor bolts will have problems under the action of long-term mechanical friction. When problems occur, the engine oil pan must be removed, and the use of the engine bearings must be carefully checked to check whether the gap between the bearings is too large. If the gap is too large, it must be replaced in time.

When replacing stud bolts, the connecting rod bolts must also be replaced. Some large equipment such as nail making machines should be stopped and checked in time if the engine is not running very stably or there is an abnormal sound during normal operation to avoid greater problems.

During each maintenance, the newly replaced stud bolts and other newly replaced accessories must be checked. The focus of the inspection is on the head and guide part of the stud bolts. It is also necessary to strictly check whether there are cracks or dents in each part of the thread, and check whether the tooth shape of the stud bolts has changed.

Check whether the pitch is abnormal. If there is an abnormality, it must not be used again. The torque wrench should be used when installing the connecting rod cover. It must be tightened according to the specified standards. The torque should not be too large or too small. Also pay attention to selecting stud bolts and studs from supporting manufacturers.