RU2358855C1 - Method of producing grinding wheel with axially shifted cutting layer by means of air-abrasive jet - Google Patents

Abstract

FIELD: production processes.

SUBSTANCE: proposed invention can be used in producing grinding wheels with axially shifted cutting layer based on vulcanite-, bakelite- and gliptal resin-based binders. A continuously rotating shaft from easily destructible material supporting easily destructible disks, that define the grinding wheel height, is placed in the drying chamber. A binder layer is applied on the aforesaid shaft and leveled by a knife, the binder amount being adjusted by varying the gap between the said knife and shaft. Now, abrasive material is forced with the help of nozzle and air jet allowing for conditions of fixing the grinding material in the binder. Note that the density of applied abrasive material is adjusted by its amount fed and shaft rotational speed. A dash device removes loose diamond-abrasive grains. The speed of rotation of the said shaft is selected to allow preliminary drying of every layer.

EFFECT: expanded performances, lower costs.

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Description

The method relates to mechanical engineering, in particular to the formation of grinding wheels with an axially offset cutting layer, which allows to reduce the heat stress of the process of diamond abrasive processing.

A known method of forming intermittent grinding wheels (reducing heat stress of the diamond abrasive process, but having a number of significant drawbacks) on a bakelite bond, including sieving of diamond abrasive grain, mass preparation, pressing, bakelization and control [1. Yakimov A.V. Optimization of grinding processes. - M.: Mechanical Engineering, 1975-S.98 ... 99. 2. Abrasive materials and tools: Industry. cat. VNIIASH-M .: VNIITEMR, 1990.-S.110 ... 118].

The production of diamond abrasive wheels by the pressing method is limited by the scope of application of tools on a bakelite bond, the absence of special technological equipment, and the complexity of the design of the mold for the manufacture of grinding wheels with an axially offset cutting layer.

Known for a continuous method of forming a diamond-abrasive cutting layer on a grinding skin, including the basic technological operations [2. Abrasive materials and tools: Industry. cat. VNIIASH-M.: VNIITEMR, 1990.-S.126 ... 128]:

drawing the main layer of the ligament on the working side of the base on the applicator machine, followed by leveling the layer (with brushes, a knife or rollers);

applying a diamond-abrasive cutting layer to the base on a gravitational installation and pressing it into the bundle layer with a rotating roller;

pre-drying the main layer of the binder in a pre-dryer;

applying the fixing layer of the ligament to the side of the base with a diamond-abrasive cutting layer on an applicator;

drying the fixing layer in the main dryer. Drying temperature from 30 ... 140 ° С depending on the type of binder. The manufacture in a known manner is limited by the scope of application of tools on a fabric basis, the absence of special technological equipment, as well as the unsuitability of the method for the manufacture of grinding wheels with an axially offset cutting layer.

The objective of the invention is the expansion of technological capabilities for the manufacture and restoration of grinding wheels on volcanic, bakelite and glyphthalic ligaments, reducing the cost of manufacturing wheels, which does not require expensive special technological equipment and allows you to obtain complex profiles, for example, grinding wheels with an axially offset cutting layer [3. RF patent No. 2275294, IPC B24D 5/02, B24B 55/02. Sinusoidal diamond abrasive wheel. Stepanov Yu.S., Katunin A.V., Afanasyev B.I., Katunin A.A., Samoilov N.N., Fomin D.S. Application 2004128013/02, 09/20/2004; 04/27/2006. Bull. No. 12].

The problem is solved by the proposed method of forming a grinding wheel in conditions of separate supply of a liquid binder and grinding material, while on a continuously rotating axis of easily destroyed material, on which are installed easily destroyed wheels that determine the height of the grinding wheel, and located in the drying chamber, a layer of binder is applied, followed by leveling with a knife, and the amount of applied ligaments is regulated by changing the gap between the knife and the axis, then grinding material is fed using pla and air stream under pressure from the condition of fixing the grinding material in the bundle, while the application density of the grinding material is controlled by the amount of grinding material supplied and the axis rotation speed, and diamond-abrasive grains loose in the bundle are removed by a fencing device, in addition, the axis rotation speed is assigned from pre-drying conditions for each layer.

Features of the proposed method are illustrated by drawings.

Figure 1 presents a diagram of the formation of the grinding wheel with an axially offset cutting layer having a hub and a sinusoidal peripheral surface, side view; figure 2 is a section aa in figure 1; figure 3 - drying chamber with formed grinding wheels with an axially offset cutting layer, top view, the top cover is conditionally removed; figure 4 - element B in figure 2, leveling with a knife the first layer of the ligament; figure 5 is a cross-section bb in figure 1, applying the first layer of grinding materials and pressing them into a layer of ligaments; in Fig.6 - element B in Fig.2 after two revolutions with two layers of ligament and grinding material applied; 7 is a grinding wheel with an axially offset cutting layer having a hub and a sinusoidal peripheral surface, side view, partial longitudinal section [3. RF patent No. 2275294, IPC B24D 5/02, B24B 55/02. Sinusoidal diamond abrasive wheel. Stepanov Yu.S., Katunin A.V., Afanasyev B.I., Katunin A.A., Samoilov N.N., Fomin D.S. Application 2004128013/02, 09/20/2004; 04/27/2006. Bull. No. 12]; in Fig.8 is a General view of the grinding wheel with an axially offset cutting layer having a hub and a sinusoidal peripheral surface.

The proposed method serves for the formation of conventional, intermittent and with an axially displaced cutting layer of disk grinding wheels, as well as to restore the original working size of worn wheels, based on the growth of diamond-abrasive layers on a liquid consistency bond, followed by solidification in the drying chamber.

Before the start of the forming process, an axis 1 and side disks 2, determining the height L and the outer diameter D of the formed grinding wheel, are made of readily destructible material (for example, cardboard, plastic, etc.). The assembled frame, consisting of an axis 1 and disks 2, for the manufacture of several circles 3 (according to FIGS. 2 and 3 for four circles) is installed in the drying chamber 4 with the possibility of rotation with the speed U _f forming the tool.

The main technological transitions are accomplished with the help of two nozzles, a knife and a breaker device with continuous rotation of axis 1 with disks 2.

To supply a liquid binder from a separate container (not shown), a nozzle 5 is used, the width l of which depends on the height L of the circle minus the side gaps Z. The nozzle 5 makes a radial feed S _p equal to the thickness of one layer applied per revolution of axis 1, and longitudinal S _pr feed equal to the amplitude of A _{with a} sinusoidal circle.

To straighten the layer of a consistent binder, a knife 6 is used, making feed motions S _P and S _pr synchronously with the movement of the nozzle 5. The amount of binder applied is controlled by changing the gap between the knife 6 and the previous layer of the bundle, and when forming normal circles, the nozzle 5 can perform the functions of the knife 6.

To feed the grinding material from a separate container (not shown), a nozzle 7 is used, the width l of which depends on the height L of the circle minus the side gaps Z. The nozzle 7 performs a radial feed S _P equal to the thickness of one layer applied per revolution of axis 1 and longitudinal S _pr feed when forming sinusoidal circles. Grinding material is supplied by means of an air-abrasive jet under pressure from the condition of fixing diamond-abrasive grains in a bundle.

The fixing of the diamond-abrasive grains takes place in the drying chamber 4, where the next layer of the binder gets into the diamond-abrasive grains embedded in it during continuous rotation of the axis, where the binder hardens. Loose in a bunch of diamond-abrasive grains, passing the drying chamber, are removed by a jack device 8.

The operation of forming grinding wheels is carried out in a continuous way by sequentially filling each of the compartments formed by disks 2 (in FIG. 3, four compartments can be distinguished, i.e. four diamond-abrasive wheels are formed), and consists of the following transitions:

applying a layer of ligament on axis 1 between the separation discs 2, followed by leveling the layer with a knife 6. The amount of applied ligament is controlled by changing the gap between the axis 1 and nozzle 5 for the first layer and the previous layer and nozzle 5 for subsequent layers;

the grinding material is applied to the ligament layer mechanically using compressed air supplied under pressure to the nozzle 7 with a continuously rotating axis. The grinding material can be applied to the binder layer using compressed air in an electrostatic way, in which the grinding material is oriented so that the major axis of the abrasive grains is located radially to the axis of the circle. Thus, a layer of radially spaced grains is deposited on the axis, as a result of which the cutting ability of the wheel increases. The application density of the grinding material mechanically using compressed air is controlled by the amount of grinding material supplied from the feeder (not shown) and the compressed air pressure in the electrostatic method — the voltage at the electrodes (not shown) and the distance between them. Loose abrasive grains that have passed through the drying chamber are removed using a jacking device;

drying the next layer of binder with embedded diamond-abrasive grains in the drying chamber with continuous rotation of the axis. Drying temperature - from 30 ° С to 130 ° С depending on the type of binder.

After reaching the desired outer diameter, the workpieces are finally dried in a drying chamber for 4 ... 5 hours at a temperature of 90 ... 130 ° C.

After drying the package, it is separated by breaking the axis and side discs and the resulting circles are subjected to inspection for cracks, chips, bubbles and other defects. Next, measure the actual hardness of the circles and mark them.

Example. According to the proposed method and the developed technology, diamond abrasive wheels with an axially offset cutting layer (ARS) of 350 × 40 × 127 mm in size were manufactured for grinding gray cast iron SCh 15. Circles with a hardness of SM made of grinding grain EB 15-25 with filler made of pulverbakelite .

In ordinary circles, obtained by the traditional method of pressing, the larger the diameter of the circle, the more difficult it is to obtain a uniform density in all its parts. The particles of the mixture under compression pressure practically do not mix in planes perpendicular to the direction of pressing. This disadvantage is eliminated by forming circles with the APC of the proposed method.

Comparative tests of manufactured circles with ARS showed that they have a sufficient margin of safety and are completely safe to use. Their operating conditions are no different from ordinary. Before installing on the spindle of the grinding machine, circles with APC were subjected to static and dynamic balancing. During grinding and dressing with a diamond-metal pencil, no breakages or chipping of the cutting sinusoidal protrusions were observed.

The method allows you to easily switch to the manufacture of circles with an axially displaced cutting layer of various diameters D, amplitude a _c and sinusoid pitch t, as well as traditional types of PP, K, 3P, 2P, PV, CC, PVD, PVDS, ChK, T, 1T , PVC, PVDC, PN, cutting wheels, etc.

The method allows the manufacture of circles with different granularities in depth in order to combine rough and finish grinding by feeding an air-abrasive jet into the nozzle with grains of different granularities for each revolution of the disk with a peripheral cutting layer.

The method allows you to restore the original working size of the worn circles, based on the build-up of diamond-abrasive layers on a liquid grease on the remaining original hub, followed by solidification in the drying chamber.

The proposed method extends the technological capabilities of the manufacture and restoration of grinding wheels on volcanic, bakelite and glyphtal bonds, reduces the cost of manufacturing the wheels, does not require expensive special technological equipment and allows you to obtain sophisticated grinding wheels.

Claims (1)

A method of forming a grinding wheel, including the separate supply of a liquid binder and grinding material, characterized in that the continuously rotating axis of easily destroyed material, on which easily destroyed disks determining the height of the grinding wheel are mounted, is placed in the drying chamber, a layer of binder is applied to the axis, followed by straightening with a knife , the amount of which is regulated by changing the gap between the knife and the axis, then feed the grinding material using a nozzle and an air stream under pressure from the condition akrepleniya diamond abrasive grains of the grinding material in a bundle, and the densities of the grinding coating material controlled by the amount of material supplied to the grinding and the rotation speed of the axis, which is selected from the condition of ensuring the pre-drying of each layer, and a loose bonded diamond abrasive grain is removed by a pneumatic device.

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