RU2366564C1 - Method of abrasive wheel size recovery - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: abrasive wheel side is recovered in separate feed of liquid binder and grinding material. Worn-out wheel hub with side disks is fitted on revolving mandrel. The said side disks served to define wheel sixes to be recovered. The said mandrel is located inside drying chamber. Liquid binder layer is applied onto the said hub and smoothed by knife. Binder amount is adjusted by varying the gal between the knife and mandrel. Grinding material is air-sprayed onto the binder. Abrasive material density is adjusted by varying mandrel r.p.m. that is selected proceeding from the necessity of preliminary drying of every layer. Loose diamond-abrasive grains are removed by turnback device.

EFFECT: expanded performances, lower costs.

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Description

The method relates to mechanical engineering, in particular to the restoration of the working size of grinding wheels of a conventional design, intermittent, as well as with an axially offset cutting layer, which allows to reduce the heat stress of the diamond abrasive process.

A known method of restoring the working size of a diamond-abrasive wheel, based on the regulation of the individual parts of the intermittent assembly, consisting of individual segments of the circle.

The disadvantage of this method is the high complexity of restoring the working size of grinding teams of intermittent circles, the limited use of the method only for prefabricated wheels, which have hollows and protrusions that cause vibration and impair the quality of the processed surface.

There is a method of restoring the working size of a diamond-abrasive tool from a plastically deformable bond after heating by hot pressing in a confined space, which is formed by the tool body, two master counter-templates to it and a punch-template, while the dimensions and shapes of the punch-template should provide an impact on diamond abrasive layer [A.S. USSR 214342, B24D 5/04. Application 1055448 / 25-8, 11/14/1966; 03/20/1968. Bull. No. 11].

The disadvantage of this method is the limited application and narrow technological capabilities, as well as the complexity of the method, the high cost and high complexity of restoring the working size of the grinding tool.

The objective of the invention is the expansion of technological capabilities for the restoration of grinding wheels on volcanic, bakelite and glyphthalic ligaments, reducing the cost of restoration of wheels, saving expensive diamond-abrasive material. The restoration does not require expensive special technological equipment and allows you to get complex, for example, grinding wheels with an axially offset cutting layer [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 restoring the working size of the grinding wheel on an organic bond, and recovery is carried out under conditions of separate supply of a liquid bond and grinding material, while the hub remaining after the most worn-out wheel with side disks fixed to its ends determining the height and outer diameter of the restored grinding wheel a circle, set on a rotating mandrel, which is placed in the drying chamber, a layer of liquid bond is applied to the hub ki, followed by leveling with a knife, the amount of which is controlled by changing the gap between the knife and the mandrel, then sanding material is supplied using a nozzle and an air jet under pressure from the condition of its fastening in the bundle, while the density of application of grinding material is controlled by the amount of grinding material supplied and the speed of rotation of the mandrel , the value of which is selected from the condition for ensuring preliminary drying of each layer, and diamond-abrasive grains of grinding material not fixed in a bundle lyayut pneumatic device.

Features of the proposed method for restoring the working size of the grinding wheel are illustrated by drawings.

Figure 1 presents a diagram of the restoration of the peripheral maximum worn to the hub of the working surface of the grinding wheel, side view; figure 2 is a cross section aa in figure 1; figure 3 - drying chamber with a package of restored grinding wheels, top view (relative to figure 1), the top cover of the drying chamber is conditionally removed; figure 4 - element B in figure 2, leveling with a knife the first layer of the ligament applied to the hub of the restored circle; 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 is a section bb in Fig.1 after two revolutions with two layers of ligament and grinding material deposited on the hub; in Fig.7 - a grinding wheel with the periphery completely restored on the old hub, where conventionally in the form of concentric circles extended diamond-abrasive layers on an organic bond are shown; on Fig - grinding wheel with an axially offset cutting layer having a hub and a sinusoidal peripheral surface, side view, partial longitudinal section [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]; figure 9 is a General view of the grinding wheel with an axially offset cutting layer having a hub and a sinusoidal peripheral surface; figure 10 is a section aa in figure 1, the restoration of the grinding wheel with an axially offset cutting layer; figure 11 - drying chamber with restored grinding wheels with an axially offset cutting layer, top view, the top cover is conditionally removed.

The proposed method serves to restore the original working size of worn circles, based on the build-up of diamond-abrasive layers on a liquid grease, followed by solidification in the drying chamber, as well as for the formation of conventional discontinuous disk grinding wheels with an axially offset cutting layer.

The proposed method allows to restore the original working size of the grinding wheel on an organic bond. Recovery is carried out under conditions of separate supply of a liquid ligament and grinding material.

Before starting the recovery process, a hub 2 is installed on the mandrel 1, remaining after the most worn out circle, and side disks 3, which determine the height L and the outer diameter D of the restored grinding wheel.

On the mandrel 1 can be installed a package with several worn hubs 2 and side discs 3 (see figure 2, which shows a package of 4 hubs).

The mandrel 1 assembly is installed in the drying chamber 4 and attached to an individual drive (not shown), which provides rotation with the ability to control the speed V _f .

The main technological transitions are accomplished with the help of two nozzles, a knife and a breaker device with continuous rotation of the mandrel 1 with hubs 2 and discs 3.

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 the mandrel 1.

A layer of a consistent ligament is applied to a worn hub 2, followed by leveling with a knife 6, which makes radial feed movements S _P synchronously with the movement of the nozzle 5. The amount of applied ligament is controlled by changing the gap between the knife 6 and the previous layer of the ligament.

Following the supply of the ligament, the grinding material is supplied using the nozzle 7 and an air stream under pressure from the condition of fixing the grinding material in the ligament. The application density of the grinding material is controlled by the amount of grinding material supplied and the speed of rotation of the mandrel 1, and loose diamond abrasive grains that have passed through the drying chamber are removed by a fencing device 8. The rotation speed of the mandrel 1 is assigned from the drying condition of each layer.

The nozzle 7 makes a radial feed S _P equal to the thickness of one layer applied per revolution of the mandrel 1. After the restoration of one circle, the longitudinal S _{PR is} communicated to the nozzle 5, knife 6, nozzle 7, and fender device 8 and the next circle is restored, etc.

The supply of grinding material is carried out using an air-abrasive jet into the nozzle 7 under pressure from the conditions of introduction and fixing of diamond-abrasive grains in a bunch.

The final fixing of the diamond-abrasive grains occurs in the drying chamber 4, where the next layer of the bundle with the diamond-abrasive grains embedded in it falls during continuous rotation of the mandrel 1, where the bundle hardens. Loose in a bunch of diamond-abrasive grains, passing the drying chamber, are removed by a jack device 8.

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

applying a layer of ligaments on the mandrel 1 between the separation discs 3, followed by leveling the layer with a knife 6. The amount of applied ligaments is controlled by changing the gap between the mandrel 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 mandrel 1. The grinding material can be applied to the ligament layer using compressed air can be electrostatic, in which the grinding material is oriented under the influence of electrostatic field forces 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 hub, as a result of which the cutting ability of the circle is increased. 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 rotation speed of the mandrel, with the electrostatic method, by the voltage at the electrodes (not shown) and the distance between them. Loose in the bunch of abrasive grains that have passed through the drying chamber 4, are removed using the jacking device 8;

drying the next layer of the binder with embedded diamond abrasive grains in the drying chamber 4 with continuous rotation of the mandrel 1. The drying temperature is from 30 ° to 130 ° 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 °.

At the end of the drying of the bag, it is disassembled and the recovered circles obtained are checked 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 dimensions of 350 × 40 × 127 mm were restored for grinding gray cast iron SCh 15. Circles of hardness SM were restored from grinding grain EB 15-25 with filler made of pulverbakelite.

In ordinary circles obtained by the traditional pressing method, 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 when restoring the circles of the proposed method.

Comparative tests of the restored circles showed that they have a sufficient margin of safety and are completely safe in operation. The conditions for their operation are no different from ordinary all-pressed circles. Before installation on the spindle of the grinding machine, the restored circles were subjected to static and dynamic balancing. During grinding and dressing with a diamond-metal pencil, no breakage or chipping of the cutting edges was observed.

The method allows you to easily switch to the restoration 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 you to restore 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 to restore the original working dimensions of worn circles with an axially offset cutting layer by growing diamond-abrasive layers on a liquid grease on the remaining hub, followed by solidification in the drying chamber, and also to form anew completely grinding wheel.

The proposed method extends the technological capabilities of the restoration of grinding wheels on volcanic, bakelite and glyphthalic ligaments, reduces the cost of restoration of the wheels, allows you to save expensive diamond-abrasive material, does not require expensive special processing equipment and allows you to obtain sophisticated grinding wheels.

Claims (1)

A method of restoring the working size of an organic bonded grinding wheel, characterized in that the restoration is carried out under conditions of separate feeding of the liquid bond and grinding material, with the hub remaining after the most worn-out wheel with side disks fixed to its ends determining the height and outer diameter of the restored grinding wheel , mounted on a rotating mandrel, which is placed in a drying chamber, a layer of a liquid binder is applied to the hub, followed by leveling m knife, the amount of which is controlled by changing the gap between the knife and the mandrel, then feed the grinding material using a nozzle and an air jet under pressure from the condition of its fixing in a bundle, while the density of application of the grinding material is regulated by the amount of supplied grinding material and the rotation speed of the mandrel, the value of which they are selected from the condition of ensuring preliminary drying of each layer, and diamond-abrasive grains of grinding material not fixed in the bundle are removed with a jacking device.

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