RU234209U1 - Hammer (knife) for hammer mill for crushing fibrous materials such as cellulose - Google Patents

Abstract

The utility model is intended for crushing fibrous material, including cellulose. The objective of the utility model is to create a hammer that breaks cellulose into individual fibers, leaving no pieces of undercrushed raw material, and this is achieved by using a hammer in the form of a rectangular plate with two holes for hinged installation on a rotor finger, expanding to the height of the side teeth located along the perimeter of the side and end faces from the center line of the mounting holes of one side face to the center of the mounting holes of the opposite side face, characterized by the fact that the faces of the first teeth have the shape of a concave arc on one side, allowing raw material particles to slide off it, and a straight line on the other, and the teeth on the corners of the plate are made feather-shaped for a closer fit with the sieve, the two outer teeth of which have an acute angle, and the central tooth is straight. Also, such arrangement of teeth on the side and end faces of the hammers allows not only to work effectively with fragile materials having a crystalline structure, but also with fibrous materials, since fibrous materials slide off smooth hammers, and thus the efficiency of the unit decreases, since the energy spent on breaking the material must be spent several times more due to the material slipping and repeated crushing. Due to the arrangement of teeth at the ends of the hammer, it is possible to turn the knife 4 times when the teeth wear out on one side, increasing the service life of the crusher. Hammers (knives) can be used on any hammer crushing plant, if the task is to completely or partially de-fiber cellulose, and can be made of any grade of structural steel, for example: 09g2s, HARDOCK, only the service life of the hammers will depend on this.

Description

The utility model relates to devices for crushing materials based on wood pulp, waste paper, paper and other fibrous organic materials in hammer mills.

In recent years, hammer crushers have been increasingly used in various industries to process materials and production waste.

The main advantages of hammer crushers are compactness; high productivity with low energy consumption; simplicity of design and operation, which simplifies repair and maintenance; the possibility of using additional elements - sieves, which allow separating the finished product of a given size; reliability in operation.

The design of hammer crushers (Fig. 1) assumes the presence of a housing (crushing chamber), in which a rotor shaft is installed horizontally or vertically. The so-called hammers (beaters) are freely suspended on this shaft. These are crushing elements in the form of plates, made of impact-resistant steel alloys. Under the rotor with hammers, as a rule, a steel classifying sieve is fixed. The diameter of the holes in the sieve can be different - in the range from 5 to 20 mm. The sieve may not be used if there is no need to separate the finished product into fractions. An asynchronous electric motor, which can be equipped with a frequency converter, is mainly used as a drive.

The main technical characteristic of a hammer crusher is its volumetric productivity. It directly depends on the length, diameter of the rotor and its rotation frequency. Also, the efficiency of the installation largely depends on the type of the recycled raw material. The usual rotation frequency of the crusher is 1000-3000 rpm.

A prerequisite for stable operation of the system is a uniform feed of the source material. Delays in the time of power supply will lead to a decrease in average productivity. But short-term overloads can provoke clogging of the working space with product particles. As a result - a strong imbalance of the rotor, which can cause a breakdown of the machine and / or cutting of the mounting bolts.

The design and operation of a hammer crusher is quite simple.

The feedstock is fed into the machine's working chamber from above, falling onto the rotor. Hammers strike the lump feedstock with a frequency that depends on the shaft's rotation frequency, causing it to break up. Under the action of natural gravity, the crushed material is discharged downwards. A combined method of removal is often used, which involves both gravitational sedimentation and forced suction by a fan. In this case, dust and other small fractions are removed from the working area by an air flow. The finished granular product is cleaner.

Requirements for crusher knives

Crushing plants are used by industrial enterprises to crush various types of materials: paper, plastic, wood, etc. High-quality separation and crumbling of raw materials is ensured by special tools - crusher knives. Depending on their design and technical characteristics, solid minerals, building materials, chemical raw materials, abrasive materials, solid municipal waste, plant materials, etc. can be crushed. The manufacture of crusher knives requires a professional approach, consideration of technical requirements and analysis of the operating conditions of the future tool.

In hammer crushers, raw material is crushed using hammers. Additional crushing occurs when the raw material hits the walls of the crusher housing.

Hammers of hammer crushers are plates that are fixed on the drum disk. The hammers rotate at high speed together with the raw material. The material is crushed by numerous blows on the hammers and the walls of the chamber. The crushed fragments are extracted from the crusher through the grate bars.

The hammer crusher differs from the rotary crusher in its operating principle.

The raw material rotates in the drum at high speed, crushing occurs due to the collision of particles with the walls of the housing. The size of the fractions is regulated by a sieve through which the finished material is poured. This equipment is noisier than rotary analogs, and also generates more dust. The material of the crusher hammers is wear-resistant. The hammers are made of 30 KhGSA steel with subsequent hardening with a hardness of HRCэ 45 ... 50. The hammer has increased resistance to impacts. To increase the number of impact angles, it can be given an irregular shape.

The production of knives for crushers requires the following from the future tool: high blade hardness; wear-resistant edge; optimal weight; ease of installation and removal of the knife from the equipment; long service life. To meet these requirements, knives are made of high-strength steel of various grades.

Hammers with two holes for their hinged installation on a rotor pin with teeth are known from the field of technology. The rotor is placed in a grinding chamber, and during the operation of such a crusher, the raw material enters the grinding chamber, intersecting with the rows of hammers of the rotating rotor, being repeatedly subjected to their impacts, and is thrown onto the sieves. The destruction of the raw material occurs as a result of multiple hammer impacts and abrasion against the surface of the sieves. When the raw material particles reach a size smaller than the diameter of the sieve holes, they are removed from the crusher grinding chamber. In this case, under-crushed fibers stick to the side surface of the hammers, reducing the force of their impact, and clog the sieve holes, preventing the removal of the already crushed product from the grinding chamber. This leads to an excessive accumulation of already crushed and under-crushed raw material particles in the crusher grinding chamber, which actually stops the grinding process. To eliminate this drawback, manufacturers began to use hammers with sharp side edges, due to which the raw material particles are not only subjected to impact, but also to cutting, thereby increasing the efficiency of grinding. However, when grinding wet raw materials, the problem of fibers sticking to the side surfaces of the hammers remains, and the sieve remains due to the fibers sliding off the smooth sharp edges.

A hammer for hammer crushers is known (patent SU 32503), comprising a hammer body with an opening for its hinged suspension on an axis, distinguished in that, in order to reduce the time for rearranging the hammer when its working surface wears out, the opening for its hinged suspension is made in the form of a groove with rounded ends, located along the hammer body.

A known attachment for crusher hammers (patent RU 147810) contains a plate located parallel to the axis of rotation of the rotor, secured to the ends of the hammers using at least one stand with a hole for fastening with a pin, characterized in that the plate has a serrated sharpening on the working surfaces, or a serrated sharpening on the outer working surfaces, or a serrated sharpening on the outer and inner working surfaces.

A hammer crusher hammer is known (patent RU 1036366), having a shape in the form of a plate, for example, with a toothed end surface, in which holes are made for its fastening. On the rotor in its middle part, the hammer has a bending zone, while its ends remain flat. Such a design of the hammer allows to keep the design of its hinge joint with the rotor unchanged. When the crusher rotor rotates, the hammer delivers effective blows to the material being ground and, due to its design in the form of a propeller, ensures the rebound of a significant part of the crushed particles to the side at an angle to the plane of rotation of the hammer, moving the ground along the axis of the crusher rotor. This is also facilitated by the air flow created by the hammers curved like a propeller, working like the blades of an axial fan. The bending angle of the middle part of the hammer around its longitudinal axis is determined based on the crusher design, the parameters of its hammers, their operating mode, the material being ground and the degree of its grinding. With optimal bending angles of the hammers, the movement of the material being ground in the direction of the crusher axis in one or both directions, uniform load on all hammers, increased crusher productivity and more uniform wear of its working parts with an increase in the time of their repair-free operation are ensured.

Also known is a hammer for a hammer crusher (patent SU 636025), made in the form of a stepped plate with holes for fastening, characterized in that, in order to increase the efficiency of the crushing process, one of the side surfaces of each stage is provided with a protrusion, and the protrusions of two adjacent stages are located on their opposite sides with an inclination angle of 60-90°.

A hammer for hammer crushers is known (patent SU 158745), made in the form of a plate with teeth on the working edges and pivotally attached to the crusher rotor, characterized in that, in order to maintain a constant optimal gap between the sieve or deck of the crushing chamber and the working edge of the hammer, and also to increase the service life of the latter, it is made in the form of an equilateral triangle with convex sides and three mounting holes for fastening, located at the vertices on the geometric axes of the triangle.

A fibrous plant material crusher is known (patent RU 205978), in which a rotor is mounted on a vertical shaft with sets of hammers fixed to it, which are rectangular plates with two axial openings at the ends, the side faces of which are cut at an angle of 45°, and half of the sets of hammers are replaced by sets of knives in such a way that the hammers and knives alternate along the circumference of the rotor disk, and the side faces of the hammers are cut at an angle of 45° from the upper and lower sides towards the middle of the face and form a cutout triangular in cross-section.

The disadvantage of these hammers is that when crushing fibrous material, including cellulose, on smooth or stepped hammers, the raw material is not de-fibered, and flakes pass through the sieve, which is unacceptable in fiber production.

The objective of the utility model is to create a hammer that breaks cellulose into individual fibers without leaving pieces of under-crushed raw material.

The technical result consists in increasing the efficiency of the crusher due to more uniform grinding of raw materials (cellulose) into fibers by the side faces and subsequent regrinding by the end faces.

The technical result is achieved by means of a hammer (Fig. 2) in the form of a rectangular plate with two holes for hinged installation on the rotor finger, expanding to the height of the side teeth located along the perimeter of the side and end faces from the center line of the mounting holes of one side face to the center of the mounting holes of the opposite side face, characterized by the fact that the faces of the first teeth have the shape of a concave arc on one side (Fig. 3), allowing raw material particles to slide off it, and a straight line on the other, and the teeth on the corners of the plate are made in a feather shape for a closer fit with the sieve, the two outer teeth of which have an acute angle, and the central tooth is straight.

Such arrangement of teeth on the side and end faces of the hammers allows to break the cellulose into individual fibers, since fibrous materials slide off smooth hammers and thus the efficiency of the unit decreases, since the energy spent on breaking the material must be spent several times more, due to the material sliding off and repeated crushing. Thus, without leaving pieces of under-crushed raw material, the teeth on the end of the hammer serve to grind the pieces of raw material that ended up on the sieve, due to the creation of a turbulent flow on the surface of the sieve, thereby forcing the remains of the raw material to fly off the sieve and get under the side surface of the hammer (knife).

The hammer, due to the arrangement of the teeth at the ends of the hammer, allows the knives to be turned over 4 times when the teeth on one side wear out, increasing the service life of the crusher.

The hammer solves the task, since the sharpened teeth cope with the task 50-75% better than smooth or stepped ones, all other things being equal. In this case, the side teeth perform the function of primary grinding of cellulose, and the end teeth perform the function of tearing pieces into fibers.

Hammers (knives) can be used on any hammer crushing plant if the task is to completely or partially de-fiber cellulose and can be made of any grade of structural steel, for example: 09g2s, HARDOX, etc., only the service life of the hammers will depend on this.

Operating principle.

The incoming material enters the crusher into the crushing chamber where, hitting the hammers hinged on the axis, it is crushed due to the impact force of the teeth covering the end of the hammer and its side parts, since it is in these places that the crushing of the material of the side teeth occurs. Getting into the crushing zone, the raw material, due to the centrifugal force, tends to the periphery of the crushing zone, thereby ending up in the working zone of the teeth. The impact and cutting force is created due to the centrifugal forces when the rotor rotates from 750 to 3000 rpm. Bouncing particles of raw material, including from the sieve, fall under the end and side teeth and are also crushed. The particles of raw material remaining on the sieve, due to the creation of a turbulent flow from the end teeth on the surface of the sieve, are again fed under the side teeth for additional crushing.

The sieve is installed to calibrate the material. If it is necessary to obtain flakes or fibers of a certain size after the crusher, then a sieve with the corresponding hole diameter is installed.

The material is not able to fly out of the crushing zone until it has reached a size smaller than the diameter of the holes on the sieve. Depending on the sieve, the degree of fiberization of sheet cellulose (paper, waste paper) can be determined to individual fibers.

The finished material leaves the crusher only after the pieces of crushed material reach sizes smaller than the holes in the sieve.

The service life of one side of the teeth depends on the type of raw material, the steel from which the hammers are made, and the installed sieve. Due to the arrangement of the teeth at the ends of the hammer on four sides: at the top and bottom of the plate, on the front and back sides, it allows you to turn the knives 4 times when the teeth on one side wear out, increasing the service life of the crusher without replacing the knives.

Claims (1)

A hammer for a hammer crusher for crushing fibrous materials in the form of a rectangular plate with two holes for hinged installation on a rotor finger, expanding to the height of the side teeth located along the perimeter of the side and end faces from the center line of the mounting holes of one side face to the center of the mounting holes of the opposite side face, characterized in that the faces of the first teeth have the shape of a concave arc on one side, allowing raw material particles to slide off it, and a straight line on the other, and the teeth at the corners of the plate are made in the form of a triple tooth for a closer fit with the sieve, the two outer teeth of which have an acute angle within 35-60°, and the central tooth is straight.