In conditions of small-scale production, as well as in everyday life, external threads are cut using a special cutting tool - dies. That is why a universal die holder must have any sensible owner in its arsenal. By selecting the dies, you can adjust the diameter of the thread being cut. This article describes the features of using die holders, gives recommendations for 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 process, he experiences enormous loads. In addition, in the cutting zone, the surface of the metals is heated to 500-600 degrees Celsius. Therefore, for the manufacture of dies and taps in Russia, P6M5 high - speed steel is used , which contains up to 5% molybdenum. It is thanks to the content of this chemical element that steel has such a high wear resistance and red crack resistance.
Varieties of dice
The most popular and popular are metric threads M3-M14. Universal die holder can work with any size of the cutting element. But there are other types.
Another highlight is 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 nevertheless periodically arises. A distinctive feature of 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 plates of high speed steel.
How to fix a die
The design of the universal die holder provides for special mounting bolts around the perimeter. Along the perimeter of the outer cylindrical surface of the die there are blind holes to a small depth. Fixing bolts, getting 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 say the surface of the workpiece with machine oil. This measure will greatly facilitate the threading process and extend the life of the tool for cutting external threads. In order to cut the thread, it is necessary to rotate the ram holder with the ram fixed in it clockwise. In this case, the plane of rotation of the tool for cutting the external thread must be strictly perpendicular to the axis of the cylindrical workpiece, otherwise the die may break.
Tapping 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 sets of dies include a tool for cutting large diameter threads, their use is difficult due to the fact that it is necessary to apply an extremely large force to rotate the die holder. In such cases, the workpiece itself rotates, clamped in a three-jaw self-centering turning chuck. The handle of the die holder must be fixed in the carriage of the lathe, since it is practically 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 joints.
As already noted, in such cases, the so-called klupps, and not dies, are used as a cutting tool. The use of a screwdriver virtually eliminates the rejection of thread on the pipe.
For threading the pipe, it is advisable to use a die holder with a ratchet. This will greatly facilitate and speed up the process of threading and will allow threading on 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 kluppov
The whole variety of dies and screwdrivers can be divided into certain groups according to a number of signs and parameters. Most threads are start-up. However, there are, although rare, left-handed threads. Accordingly, dies with klupp distinguish between left-handed and right-handed.
This tool is classified by size and degree of automation of the cutting process.
Construction and principle of operation
Compared to a die, a screwdriver is a simpler product. The die is an integral 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 the pipes. This design allows for more efficient chip removal, which extends the life of the tool.
The principle of action kluppa is similar to the principle of action of the die. By rotating the tool clockwise, threading is performed on a cylindrical surface. By turning in the opposite direction, the tool is twisted.
Existing varieties of die holders
Die holders are in great demand. In pursuit of consumers, manufacturers develop and produce new models of such a tool. At the present time, on the market, in addition to the traditional holders of dies and screw cutters for thread cutting, ratchet holders and even complexes equipped with an electric drive are sold.
Each of the listed options has certain disadvantages and advantages.
A conventional die holder with a set of dies of various diameters will allow threading 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-series and mass production.
Ratchet holders have been gaining popularity recently. This simple tool allows you to easily thread 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 screw die with short jerks, and then twist 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 effort. Thus, such a holder (knob) can perform the function of a dynamometer (for this, the clamping force of the ratchet is pre-regulated). The 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 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 tools is hollow so that a pipe can pass through it.
The device and principle of operation of the hand holder
A similar tool consists of two metal rods attached to a sleeve. The die or screw die is attached using a special mounting device to this sleeve. The rotation of the tool is carried out by rotating these handle rods.
Some models are made with one handle. In particular, ratchet holders have one handle. The ability to thread in a limited space by giving the handle a rotation at a slight angle is an indisputable advantage of this model of tool. However, the ratchet device is quite complex, which is a frequent cause of breakdowns of such mechanisms. This circumstance should be taken into account when deciding to purchase a set of tools for threading.
Features of the operation of an electric tool
Power tools are professional. It is also widely universal and, thanks to a set of dies and screw dies, can cut threads of various diameters. When using such equipment, the threading process is greatly simplified, takes much less time and effort. Compared with traditional hand tools, this method of threading does not require much effort on the part of the worker. However, not everything is so smooth. There are significant drawbacks: only workers who have permission are allowed to work, the inability to thread in hard-to-reach places, the need for power supply, the inability to work in a humid environment, and so on.
Unlike a simple hand tool, a power tool needs constant care. Such a tool must be stored in a designated bedside table at a normal level of humidity and temperature. Each manufacturer gives their recommendations for the care and maintenance of the equipment. Each owner of such complex and expensive equipment is simply obliged to study the instructions.
Preparation for threading
Externally, the threading process may seem elementary simple. However, this is a mistake, 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).
The cleaning of the surface of the pipe should never be neglected. After all, the presence of scale and other inclusions can cause damage to the tool. In production, various methods of cleaning the surface of a metal are used (shot blasting, sandblasting, processing in an ultrasonic bath, etc.). At home, rust and scale are usually cleaned with sandpaper.
Rolling the pipe is also an important stage in the preparatory work. The essence of this procedure is to reduce the outer diameter of the pipe in the area of the end. 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 allow (especially the length), then it is allowed for this purpose to make a chamfer with a size slightly larger than the depth of the thread.
Tool Tips
The main task of the tool with a set of dies and screw dies is to obtain threads that meet the requirements of GOST. Universal die holder fully meets these requirements. However, when choosing dice and screwdrivers, 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 costs on this item. In such cases, it is better to buy a regular good quality hand tool instead of a ratchet holder.
When choosing a particular die (screw die), 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 grade of steel and its properties (domestic marking is intuitively clear even to a person who is 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 steel grade 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.