In conditions of small-scale production, as well as in everyday life, external threads are cut using a special cutting tool - a die. That is why a universal die holder must have any sensible owner in its arsenal. By selecting dies, you can adjust the diameter of the thread being cut. This article describes the features of using die holders, gives recommendations on their selection and operation.
Basic concepts
As the name implies, the universal die holder is designed to work with dies. The tool itself is made of ordinary structural steel. But the cutting tool (die) has special requirements. In the course of work, he experiences enormous loads. In addition, in the cutting zone, the metal surface is heated up to 500-600 degrees Celsius. Therefore, for the manufacture of dies and taps in Russia, high-speed steel R6M5 is used, which contains up to 5% molybdenum. It is thanks to the content of this chemical element that steelhas such high wear resistance and red brittleness.
Varieties of dies
The most common and popular are metric threads M3-M14. Universal die holder can work with any size of the cutting element. But there are other types.
There is also a special tool for cutting external threads on the surface of metal pipes. And although in recent years metal water pipes have been actively replaced by cheaper PVC pipes, the need for such work still periodically arises. A distinctive feature of a pipe thread is its relatively large diameter. In addition, a special tool (pipe screw die) is used to cut it. It even looks strikingly different from the usual die. The cutting elements in this case are specially sharpened high-speed steel plates.
How to fix the plate
The design of the universal die holder provides for special fixing bolts around the perimeter. Along the perimeter of the outer cylindrical surface of the die there are blind holes to a small depth. Mounting bolts, falling into these holes, securely fix the die and prevent it from turning.
Recommendations for working with dies and die holder
Before proceeding directly to threading, it is recommended to mark the surface of the workpiece with machine oil. This measure will greatly facilitate the threading process andextend the life of the external threading tool. In order to cut the thread, it is necessary to rotate the die holder with the die fixed in it clockwise. In this case, the plane of rotation of the tool for cutting external threads must be strictly perpendicular to the axis of the cylindrical workpiece, otherwise the die may break.
Cutting threads on large workpieces
For threading on a bar of large diameter, it is advisable to use a screw-cutting lathe. In this case, the turns will be cut with a specially sharpened cutter.
Although some die sets include a large diameter tapping tool, they are difficult to use due to the extremely high force required to rotate the die holder. In such cases, the workpiece itself rotates, clamped in a three-jaw self-centering lathe chuck. The handle of the die holder must be fixed in the carriage of the lathe, since it is almost impossible to hold it in your hands.
Features of pipe threading
The universal die holder can be used as an auxiliary device when cutting not only metric, but also pipe external threaded connections.
As already noted, the so-called dies are used as a cutting tool in such cases, not dies. The use of a die cutter practically eliminates getting a defective thread on the pipe.
For threading a pipe, it is advisable to useratchet holder. This will greatly facilitate and speed up the process of threading and allow you to thread pipes in the most inaccessible places.
The presence of a chamfer on the end surface of the pipe will greatly facilitate the process of threading and eliminate the occurrence of distortions of the cutting tool.
Types of dies and klupps
The whole variety of dies and klupps can be divided into certain groups according to a number of features and parameters. Most of the threads are right entry. However, there are, although rare, left-handed threads. Accordingly, dies with screw caps distinguish between left-handed and right-handed.
This tool is classified both by size and by the degree of automation of the cutting process.
Design and principle of operation of klupps
Compared to a die, a klupp is a simpler product. The die is a one-piece tool and is made entirely of expensive high-speed steel grades. Klupp is a prefabricated structure. Its body is made of ordinary structural steel. And already cutters are attached to the body for cutting inch threads on the surface of pipes. This design allows for more efficient chip evacuation, resulting in longer tool life.
The principle of operation of the klupp is similar to the principle of the die. By rotating the tool clockwise, threading is performed on a cylindrical surface. By turning it in the opposite direction, the tool is unscrewed.
Existing varieties of die holders
Die holders are in high demand. Manufacturers in pursuit of the consumer develop and produce new models of such a tool. Currently on the market, in addition to traditional die holders and threading die holders, ratchet holders are sold, and even complexes equipped with an electric drive.
Each of the above options has certain disadvantages and advantages.
A regular die holder with a set of dies of various diameters will allow you to cut threads at home. However, it should be noted that the process is very laborious and requires a significant investment of time and effort. For this reason, this kind of tool has not found application in medium-sized and mass production.
Ratchet die holders have been gaining popularity lately. This simple tool will allow you to easily cut threads even in the most inaccessible places. It is also universal, that is, it also allows you to work with dies of various diameters. Thanks to the ratchet, you can wind the die or die in short jerks, and then unscrew it in the same way. In conditions of limited space, this design feature can eliminate the need to disassemble a complex assembly or dismantle pipes. Another important feature of such a tool is the ability to adjust the force. Thus, such a holder (knob) can perform the function of a dynamometer (for this, the clamping force of the ratchet is preliminarilyregulated). Clamping force (in this case, threading) is a critical indicator when working with thin-walled and high-precision parts and assemblies.
One electric tool can replace a whole set of die holders. However, in the conditions of a single production, the acquisition of such an expensive unit will never be justified. This tool is equipped with an electric motor capable of developing a significant torque. The spindle of such a tool is hollow so that a pipe can pass through it.
Design and operation of the hand holder
This tool consists of two metal rods attached to a bushing. The die or die is attached using a special fastening device to this sleeve. The rotation of the tool is carried out by rotating these handle bars.
Some models are made with one handle. In particular, ratchet holders have one handle. The ability to cut threads in a limited space by giving the handle rotation at a slight angle is an indisputable advantage of this tool model. However, the ratchet device is quite complex, which is a common cause of breakdowns of such mechanisms. This circumstance should be taken into account when deciding whether to purchase a threading tool kit.
Peculiarities of electric tool operation
Power tools are professional. He is alsowide universal and due to the presence of a set of dies and die cutters, it can cut threads of various diameters. When using such equipment, the process of threading is greatly simplified, it takes much less time and effort. Compared with traditional hand tools, this threading method does not require much effort on the part of the worker. However, not everything is so smooth. There are also significant drawbacks: only workers who have permission are allowed to work, the inability to cut threads in hard-to-reach places, the need for electricity supply, the inability to work in a humid environment, and so on.
Unlike simple hand tools, power tools need constant care. Such a tool must be stored in a specially designated bedside table at a normal level of humidity and temperature. Each manufacturer gives its own recommendations for the care and operation of equipment. Every owner of such complex and expensive equipment is simply obliged to study the instructions.
Preparation for threading
From the outside, the process of threading may seem elementary simple. However, this is a delusion, because this process is preceded by a complex set of preparatory work.
The stage of preparatory work when cutting pipe threads includes cleaning the surface of the pipe, rolling the pipe, applying lubricant, and securely fixing the workpiece (pipe).
Cleaning the surface of the pipe should never be neglected. After all, the presence of scale and other inclusions can causetool breakage. In production, various methods of cleaning the metal surface are used (shot blasting, sandblasting, processing in an ultrasonic bath, etc.). At home, rust and scale are usually removed with sandpaper.
Rolling the pipe is also an important step in the preparatory work. The essence of this procedure is to reduce the outer diameter of the pipe in the end area. In production, a special mill is usually used for these purposes. At home, an ordinary file can be used. If the dimensions of the pipe (especially the length) allow, then for this purpose it is allowed to make a chamfer slightly larger than the depth of the thread.
Tips for choosing a tool
The main task of the tool with a set of dies and die cutters is to obtain threads that meet the requirements of GOST. The universal die holder fully satisfies these requirements. However, when choosing dies and klupps, you must be careful. After all, only high-quality tools from trusted manufacturers can provide proper quality. Therefore, even when purchasing a tool for one-time use, it is not recommended to save on this expense item. In such cases, it is better to purchase a good quality regular hand tool instead of a ratchet holder.
When choosing a specific die (klupp), you should first of all pay attention to the material from which it is made. In the case of a domestic manufacturer, there are no difficulties in determining the steel grade and its properties(domestic marking is intuitively clear even to a person far from materials science). But a power tool of this kind is produced only abroad. And ISO standards are very different from ours. Therefore, in order to determine the grade of steel and find out its mechanical properties, you will have to work with special reference books.
As a rule, the price of a product correlates with its quality. In other words, the higher the quality, the higher the cost of the tool.
