Types of hammers and their purpose
A tool familiar from early childhood, the hammer, in the view of many people acts as a primitive tool of labor, which was still used by primitive people. Of course, this is a historical fact. But he does not detract from the role of this ingeniously simple device of shock action, which can be described with full confidence as the most effective mechanism for converting kinetic energy into mechanical work.
Bit of theory
When hammering a nail, we don’t think about the most difficult physical transformations in the hammer / nail / solid system. The coefficient of performance (the ratio of useful work and energy expended on bringing the hammer into motion) is 70 - 97%. For most modern machines and mechanisms - this is an unattainable limit.
The main part of the energy loss goes to the return of the hammer back, due to the occurrence of elastic forces. The amount of recoil depends on the material of which the hammer head is made and the properties of the material. For a steel tool, energy loss is about 30%, for a titanium one - within 3 - 5%. But these indicators also depend on other parameters:
- type and shape of the shock;
- material and handle length;
- tool mass;
- contact angle;
- compliance with the type of hammer of the operation performed.
The last item on the list is very important - in mechanical engineering, stone processing, construction, various types of hammers of different levels of versatility are used. Among them, you can choose a tool for all occasions, for domestic and semi-professional use, and highly specialized, "sharpened" for performing one or two operations, but with the highest efficiency.
The two main parts of which the hammer consists - the handle and the head, are tightly interconnected. When moving on a massive head, quite large forces act - when sliding off the handle during an impact, the kinetic energy of the head allows it to fly several tens of meters. If at the junction there was the slightest wobble or cracks appeared on the handle - the hammer should never be used. It becomes dangerous for workers and others.
The head consists of several parts:
1. Sock;
2. Hole for the handle (mounted);
3. Wedge;
4. Nail clipper;
5. Striker;
6. Cheek;
7. Lever.
The hammer head, the head shock part, usually flat, has sufficient area and strength to withstand a significant amount of shock contacts with solid objects without deformation. The impact surface is flat or slightly convex. In cross section, it represents a square, rectangle, or circle.
The back of the hammer, in most cases, is wedge-shaped. This allows you to develop a significantly greater impact force, due to the reduction of the contact area. A wedge strike is applied when it is necessary to crack the material or to mint. The back can be spherical, depending on the scope of the hammer and its main purpose.
The head is made in the form of an oval or round through hole, the walls of which slightly expand from the center to the upper part, to exclude the possibility of slipping off the handle. On some types of hammers, a shackle is provided around the landing hole in the form of a metal collar that extends several centimeters on the top of the handle. This part of the tool protects the handle from breaking in case of too strong or inaccurate impact.
The head is made of hard metal by forging, casting or milling. It is protected from corrosive effects by special types of paint or electroplated coating.Before applying the protective layer, the head is subjected to hardening, in most cases selective. The greatest hardness (up to 52 units on the Rockwell scale) is reached by the shock part (striker). Hardening is carried out by the electric induction method, which makes it possible to precisely control the depth of surface hardening. On the striker, the hardening depth reaches 3 - 5 mm.
The back part (wedge or nose) is hardened to 36 - 42, and the area of the landing hole is only 24 - 30 units on the same scale. The shape, weight, dimensions and other characteristics of industrial hammers are determined by GOST 11042-90 and 2310-77 which describe almost all types of hammers and their purpose.
Many manufacturers produce percussion instruments according to their own specifications, which take into account most of the requirements given in national standards. The changes relate to the use of new alloys, the length and shape of handles of improved ergonomics, computer-modeled, more accurate surface treatment.
Types and types of hammers
Carpenter's hammer
It differs in its shape - the back is made in the form of a "dovetail", nail clipper. In most cases, the types of hammers and their application can be accurately determined by design. As a rule, they are a double-acting tool with which you can perform several heterogeneous operations without involving other devices.
The mass of the carpenter's hammer is in the range of 300 - 800 grams. They are intended for hammering nails and wedges, fitting wooden mates. The working surface is smooth or corrugated, flat, the back, the nail gun, has a different bending angle - from its complete absence to 100 - 1200 (the so-called "California"). The first known image of a carpenter’s hammer of the usual form for us is dated 1514. You can see it in the picture of Dürer "Melancholy".
Carpentry hammers are used during installation of various load-bearing and auxiliary structures made of wood. Some types of tools have special slots on the head for nailing or a magnetized hammer that keeps the nail in position when working with one hand.
Joiners
High precision tools. It does not require as much impact force as accuracy. Produced in a wide range of mass of the head part - from 100 to 800 grams in increments of 50 grams. The shock part in most cases is perfectly flat. Rear - can be either a nail clipper or a simple wedge.
The handles are not only made of wood, there are metal and fiberglass, coated with rubber or polymer overlays to prevent slipping of the hand.
Bench hammers
They are very similar to carpentry, but with a wedge-shaped back part and a slightly convex striker, hardened to an indicator of 45 - 50 units, which prevents damage when hitting a core or chisel. The mass range is the same as for carpentry, the handles are also made of various materials, as a rule, they are coated with oil-resistant pads.
Bushhammer
Under this name, various types of hammers are combined, the distinguishing feature of which is the presence of a flat impact part and a specific rear part, designed to chip and break bricks and various stone and concrete materials. The back may be in the form of a flat or pointed pickaxe. On this basis, the mason's tool is called Berlin or Geneva.
Working with stone and ceramic materials requires increased hammer strength, so they are cemented or hardened by induction to a hardness not lower than that of a forge hammer. Among the universal tool, hammers for applying decorative notches can be distinguished. They received the name "Buchard", they can be distinguished by the presence of various kinds of protrusions, tubercles and cuts on the shock.
As in sledgehammers, the handle of a mason's hammer is inserted from above and does not wedge. The handle is often marked in the form of a ruler, which facilitates the work of a bricklayer when fitting a brick for dressing or laying complex architectural elements.
Tiler Hammer
When installing ceramic tiles, large mechanical loads and impacts are not applied. As with carpentry, accuracy is more important here. The weight of the tiler hammer rarely exceeds 75 grams, the impact part is hardened to high hardness. Such tools are used mainly for chipping off small parts of tile when fitting to size. When used, they require accuracy and accuracy.
Roofers Hammers
Depending on the roofing material used, a tool with a steel or polymer striker is selected. The handle is usually wooden. Unlike straightening, also designed to work with sheet metal, the back of the roofer hammer is a pointed wedge, like a pickaxe. It serves for punching holes in the sheet and bending folds and edges.
Hammers for installing slate roofs are different from tools for metal - they are equipped with a wider striker for slate nails and a special shaped nail puller in the back.
Leveling hammers and mallet
Designed to align deformed tin products, installation of roofs, drainage systems and other operations with sheet metal. As a rule, they are made of rubber or polyurethane, but there are also models with a metal head part equipped with interchangeable strikers of softer material.
Among straightening hammers, the inertia-free type of tool is popular, which does not give a rebound at all. Such hammers are made with a hollow shock part, in which sand or small fraction is filled. They completely absorb the response energy of the impact and the hammer, as it were, “sticks” to the work surface.
Hammers are designed for carpentry or locksmith work (different types). They are made of hardwood, molded rubber or polymeric materials and are designed for straightening, leveling and fitting large parts, as well as for working with chisels, chisels, wedges, cutters. The shock part is a rectangular parallelepiped, the handle is a tree or durable plastic, fiberglass, metal, usually of circular cross section.
Joiner's hammers can have a cylindrical or barrel-shaped shape, and locksmiths can be equipped with a wedge-shaped back. For work requiring special delicacy, the hammer head can be supplemented with leather, plastic, rubber or rubber pads and nozzles.
Sledgehammers and hammers
One of the most powerful tools is a sledgehammer - a massive tip on a long handle. Sledgehammers are used to perform various operations where high impact force and low accuracy are required - crushing stones, concrete, clogging wedges and racks, forging large parts. You can see the sledgehammers on the Egyptian and ancient Roman frescoes and paintings from the life of builders. In some cases, sledgehammers were used as powerful and effective weapons.
As a rule, sledgehammers are two-handed tools. But there are varieties for working with one hand in a confined space. The production of sledgehammers GOST 11401-75 and 11402-75 is regulated. The mass of the working part of the sledgehammer is in the range of 8 - 10 kg, but can reach 16 kg.
Sledge hammers are made by forging with subsequent hardening of the surface up to 32 units. Forging hammers are additionally equipped with steel plates on the impact part. Small forging and construction sledgehammers with a head mass of up to 2 kg are tempered to 50 Rockwell units.
The head of the sledgehammer itself is a rectangular parallelepiped or has the form of a conventional hammer with a wedge-shaped back. The wedge is perpendicular or parallel to the longitudinal axis of the handle.
The landing hole of the sledgehammer and hammer is slightly conical, with a narrowing to the bottom.The handle is inserted from above and does not require wedging, due to this form of the head, the sliding of the massive head is practically excluded. The length of the handle is correlated with the mass of the head and can reach 120 cm (mainly 80 - 90 cm).
Exotic Hammer Types
Considering the special types of hammers and their purpose, many more varieties and modifications can be distinguished, among which hammers are massively used:
Welder.
Glazier.
Drywall.
In addition to them, there are hammers of a very narrow scope, sometimes very unusual.
Concrete Expert Hammer
Designed to determine the hardness of concrete products, produced in several varieties:
- Schmidt's hammer - based on measuring the height of the rebound;
- Fizdel's hammer - the hardness of concrete is determined by the depth of the trace left on the surface with a spherical impact part;
- Kashkarov’s hammer, the most accurate of all. The strength of concrete is determined by comparing the depth of the track on concrete and the control metal plate inserted from the opposite side of the striker. The accuracy of the determination does not depend on the force of the impact and the speed of the hammer.
Back hammer
It is used in car body repair and work with thin tin. It has little in common with an ordinary hammer - it is a complex system of vacuum suction cups, hooks, bushings and other parts that interact with each other according to a rather complicated scheme.
Decorative hammers
From a completely practical device informing the owner of the arrival of guests, the door knocker, known since ancient China, has turned into an exquisite accessory, used more for decoration. It is a wooden mallet of an original form, mounted on a lace or hinge on the front door.
Judges and auctioneers
A wooden tool designed to attract the attention of an audience and notify the completion of a particular stage of justice or sales. In appearance, it somewhat resembles a mallet, but there are also very unusual products that provide genuine works of art.
Neurologist's hammer
A medical tool for determining the various nervous reactions of the search for pathologies. It is made of stainless steel and is equipped with rubber or polymer tips on both sides of the symmetrical head. Sometimes it is completed with a neurological needle hidden in the handle.
Surgical hammer
Used for striking a surgical bit or dental instruments. It is made of stainless medical steel, cast iron, brass, equipped with polymer overlays to reduce impact noise.
In addition to these tools, there are other hammers of narrow purpose:
- intrinsically safe, from beryllium or aluminum;
- wallpaper;
- kitchen, for beating meat;
- for laying mosaics;
- cooperage;
- core samples;
- geological;
- mountaineering;
- railway;
- staple-resistant.
For almost every specialty and field of activity, where impacts are expected, their types and varieties of hammers are developed.
Variety of hammer handles
In addition to the variety of shapes and sizes of the head, hammers also differ in handles. This part of the tool plays an equally important role in its functionality, determining not only the impact force and speed of movement, but also the level of fatigue of a person working with a hammer, the safety of using the tool and its durability.
Handles are made of hard wood, which is given a convenient and ergonomic oval in cross section shape, convenient for gripping. But, in addition to hardness, a certain flexibility is also required from wood, in order to reduce the recoil force, fracture resistance (viscosity), and uniform density. The following breeds are most suitable for the manufacture of handles:
- hornbeam;
- oak;
- hazel;
- hickory;
- ash;
- maple;
- birch (comel).
Exotic types of hammers and mallets can be made of mahogany and other valuable species.
Many modern tools are equipped with handles made of various types of polymers, fiberglass, even all-metal.They are certainly equipped with anti-vibration pads made of soft rubber or rubber, which reduce recoil force and increase friction between the worker’s hands and the handle.
A feature of the action of the hammer is that the maximum part of its mass should be concentrated in the region of the head part - in this case, its speed will be maximum with a minimum of effort. The optimal ratio of the strength of the handle and its weight is the main requirement in the manufacture of any type of hammer.
